1

National Emission Standards for Hazardous Air 

Pollutants:

Secondary Aluminum Production

Summary of Public Comments and Responses on Proposed Rule (77 

FR 8576, February 14, 2012) and Supplemental Proposal (79 FR 

72874, December 8, 2014)

U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Sector Policies and Programs Division

Research Triangle Park, NC 27711
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Table of Contents

Section Page

List of Acronyms and Abbreviations............................................................................................................4

Purpose and Background ..............................................................................................................................5

Commenters..................................................................................................................................................5

1. Risk Assessment .......................................................................................................................................6

1.1 Risk Assessment Inputs: Processing of ICR Data into Modeling File..........................................6

1.2 Risk Assessment Methods ............................................................................................................8

1.2.1 Modeling of MACT Allowable Emissions................................................................... 8

1.2.2 Modeling of Acute Exposure........................................................................................ 9

1.2.3 Multipathway Screening............................................................................................. 11

1.3 Uncertainties in Risk Assessment...............................................................................................12

1.3.1 Individual Variability and Exposures......................................................................... 13

1.4 Risk Assessment Results.............................................................................................................19

2. Rule Provision Changes..........................................................................................................................21

2.1 Control Device Shutdown...........................................................................................................21

2.2 Change of Furnace Classification ...............................................................................................22

2.3 Hydrogen Fluoride Compliance..................................................................................................27

2.4 Hydrogen Chloride Compliance .................................................................................................27

2.5 Operating Requirements/Work Practices....................................................................................29

2.6 Other Technical Corrections/Clarifications................................................................................32

3. Testing and Monitoring...........................................................................................................................38

3.1 Testing Uncontrolled Group 1 Furnaces.....................................................................................43

3.2 Worst Case Scenario Testing ......................................................................................................44

3.3 Reporting.....................................................................................................................................49

3.5 Other ...........................................................................................................................................50

4. Compliance Dates...................................................................................................................................51

5. Startup, Shutdown, and Malfunction ......................................................................................................52

5.1 Removal of SSM Exemption ......................................................................................................52

5.2 Startup and Shutdown.................................................................................................................64

5.3 Malfunction and Affirmative Defense ........................................................................................74

6. Regulatory Impacts.................................................................................................................................89

6.1 Cost and Economic Impacts........................................................................................................89

7. Miscellaneous Comments.......................................................................................................................92

7.1 Commenter Endorsements..........................................................................................................92

7.2 Other Comments.........................................................................................................................92
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List of Acronyms and Abbreviations

ACGIH American Conference of Governmental Industrial Hygienists

CAA Clean Air Act

CBI Confidential Business Information

CRWI Coalition for Responsible Waste Incineration

D/F Dioxins and Furans

EPA U. S. Environmental Protection Agency

ERT Electronic Reporting Tool

FAX Fascimile

FR Federal Register

HAP

HCl

Hazardous Air Pollutant

Hydrogen Chloride

HF Hydrogen Fluoride

HON Hazardous Organic NESHAP

MACT Maximum Achievable Control Technology

MIR Maximum Individual Risk

MOA Mode of Action

NAAQS National Ambient Air Quality Standards

NATA National-Scale Air Toxics Assessment

NESHAP National Emission Standards for Hazardous Air Pollutants

NFFS Non-Ferrous Founders’ Society

OM&M Operation, Maintenance and Monitoring

PB-HAP Persistent Bioaccumulative Hazardous Air Pollutant

PSD Prevention of Significant Deterioration

RTR Risk and Technology Review

SAPU Secondary Aluminum Processing Unit

SIP State Implementation Plan

SSM Startup, Shutdown, and Malfunction

TTN Technology Transfer Network

URE Unit Risk Exposure
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Purpose and Background 

On February 14, 2012, the EPA proposed revisions to the National Emission Standards for 

Hazardous Air Pollutants (NESHAP) for Secondary Aluminum Production to address the results 

of a residual risk and technology review and to correct and clarify rule requirements and 

provisions. The EPA received 12 comment letters on the 2012 proposal. On December 8, 2014,

the EPA issued a supplemental proposal that addressed a limited set of issues. The EPA received

16 comment letters on the supplemental proposal. The purpose of this document is to summarize

and respond to the comments received on the 2012 proposed rule and 2014 supplemental 

proposal that are not addressed in the final rule preamble; however, the final rule preamble also 

contains discussions of several of these topics. In the summarized comments below, we have 

indicated those comments that were submitted on the 2014 supplemental proposal. Unless 

otherwise noted, the remaining comments were received on the 2012 proposed rule. All 

comments are contained in Docket EPA-HQ-OAR-2010-0544.

Commenters

The commenter, affiliation, and item number in Docket EPA-HQ-OAR-2010-0544 are listed 

below in Table 1.

Table 1. Public Comments for Secondary Aluminum Production NESHAP, 2012 Proposed Rule

and 2014 Supplemental Proposal, Docket EPA-HQ-OAR-2010-0544

Docket No. 

EPA-HQOAR-2010-

0544 Commenter Name Affiliation

2012 Proposed Rule

0183 J. W. Vinzant Kaiser Aluminum

0189 Eileen A. Sottile LKQ Corporation

0190 Melvin Keener Coalition for Responsible Waste Incineration (CRWI)

0191 James Mallory Non-Ferrous Founders’ Society (NFFS)

0192 J. W. Vinzant Kaiser Aluminum

0193 Charles D. Johnson The Aluminum Association

0194 Mike Palazzolo Alcoa 

0195 Russell Frye SSM Coalition

0196 Marcus Cooke Cooke Companies International

0197 Shannon Broome Air Permitting Forum

0198 J. W. Vinzant Kaiser Aluminum (duplicate of 0192)

0199 G. C. Barnett Aleris International, Inc.

2014 Supplemental Proposal

0286 Jerry Call American Foundry Society

0287 G. Vinson Hellwig, 

Robert H. Colby

National Association of Clear Air Agencies

0288 G.C. Barnett Aleris
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Docket No. 

EPA-HQOAR-2010-

0544 Commenter Name Affiliation

0289 Sean O. Alteri Kentucky Department for Environmental Protection

0290 J. Roger Crawford Kaiser Aluminum

0291 Garret Morris Greater Baltimore Health Alliance 

0292 Matt Owens Century Aluminum

0293 J. Roger Crawford Kaiser Aluminum(duplicate of 0290)

0294 James D. Jones Alcoa

0295 Charles D. Johnson The Aluminum Association

0296 James L. Mallory Non-Ferrous Founders' Society

0297 Shannon Broome Air Permitting Forum 

0298 Russell Frye SSM Coalition

0299 Ronald A. Amirikian Delaware Division of Air Quality

0300 Steven Klafka Wingra Engineering

0301 Emma Cheuse Earthjustice

1. Risk Assessment

1.1 Risk Assessment Inputs: Processing of ICR Data into Modeling File

Comment #1: In a comment on the supplemental proposal, commenter 0300 stated that when 

developing the original NESHAP for secondary aluminum, the EPA removed die casting 

operations from the NESHAP. The commenter stated that it would be appropriate for the EPA to 

revisit its decision to not develop NESHAP for die casting operations. The commenter stated that 

similar to the secondary aluminum production operations, furnaces at die casting facilities have 

emissions of dioxins/furans, chlorine, hydrogen chloride and particulate and the hazardous air 

pollutants released from the partial combustion of lubricants have not be identified, and likely 

contain products of incomplete combustion such as polycyclic aromatic hydrocarbons (PAHs).

Response: This comment was not made on the 2012 proposal and is outside the scope of the 

2014 supplemental proposal, which solicited comment only on specific topics identified in the 

notice. See 79 FR at 72883-84. For informational purposes only, we have attempted to respond 

to the commenter’s concerns.

The EPA disagrees with the commenter’s statement that aluminum die casting operations were 

removed from the NESHAP and, therefore, are not subject to the NESHAP. Die casting 

operations that are substantially like operations at other secondary aluminum production 

facilities are subject to subpart RRR requirements. Specifically, a die casting facility that is a 

major source, is generally considered a secondary aluminum production facility and subject to 

subpart RRR if they operate a sweat furnace, a thermal chip dryer or a scrap dryer/delacquering 

kiln/decoating kiln. In addition, regardless of the types of operations conducted at a major source 

die casting facility, they are subject to the NESHAP if they process anything other than clean
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charge, internal scrap, or customer returns. See section 40 CFR 63.1503, definition of secondary

aluminum production facility. Like a furnace at a major source die casting facility, a furnace at 

an area source die casting facility is subject to the subpart RRR emission standards for D/F with 

one exception. A furnace operated by an area source die casting facility that would be subject to 

subpart RRR only because the facility operates a thermal chip dryer, is not subject to the 

requirements of subpart RRR if the furnace melts only clean charge, internal scrap and customer 

returns, although the thermal chip dryer would be subject. See 40 CFR 63.1500(f). Although

furnaces at die casters that are major sources of HAP would not be subject to subpart RRR if the 

furnaces handled only clean charge, internal scrap, or customer returns, and if the facility did not 

operate thermal chip dryers, delacquering/decoating kilns, or sweat furnaces, the EPA is not 

aware of any die casting facilities that are major sources of HAP that operate furnaces and are 

not subject to subpart RRR, and the commenter did not submit any contrary information.

Comment #2: In a comment on the supplemental proposal, commenter 0301 stated that the 

EPA’s data collection found emissions of mercury and other pollutants for which the EPA has 

not proposed to set any emission standards; that is unlawful under section 7412(d) and (f), and 

National Lime Association. Commenter 0301 stated that as the D.C. Circuit has held, the EPA 

has a “clear statutory obligation to set emissions standards for each listed HAP.” The commenter 

stated that the Act requires the EPA to set standards for all emitted hazardous air pollutants, and

the EPA has no lawful basis for not doing so here; the EPA must set emission standards that 

assure the maximum achievable degree of emission reduction for mercury and other emitted 

HAPs that are currently unrestricted by the Secondary Aluminum standards.

Response: The subpart RRR MACT standards have regulated most HAP since promulgation in 

2000. The standards include emissions limits for D/F, PM (as a surrogate metal HAP other than 

mercury), THC (as a surrogate for non-D/F organic HAP) and HCl (as a surrogate for acid gases 

including HF, chlorine and fluorine). 

We currently do not have sufficient data to establish emissions standards for mercury for this 

source category. To explain further, during the data collection efforts to support the RTR 

(including for developing emissions estimates and other inputs for the secondary aluminum RTR 

risk assessment), we gathered a substantial amount of emissions test data for PM, THC, HCl and 

D/F from many facilities through an information collection request (ICR). We also requested 

nine secondary aluminum companies to generate and submit compound-specific metallic and 

organic HAP data so that we could develop emissions estimates for all the HAP for input to the 

risk assessment model. The metallic HAP data collected were the measured concentration of the 

individual HAP metals in the baghouse dust. We did not collect actual emissions test data for any 

of these metal HAPs. To develop emissions estimates for each of these HAP metals for input to 

the risk model, a ratio of total PM to each HAP metal was developed based on the baghouse dust 

analyses. The ratios were then applied to the source specific PM emissions estimates to calculate 

the emissions estimates for each metal HAP for each source. This calculation approach is based 

on the assumption that the concentration of these metals in baghouse dust is the same as the 

concentration in the PM emitted from the process stack outlets. (See Development of the RTR 

Supplemental Proposal Risk Modeling Dataset for the Secondary Aluminum Production Source 

Category, EPA-HQ-OAR-2010-0544-0239). We believe this method resulted in reliable 

estimates of the emissions of the particulate metal HAPs (such as Pb, Be, Cd, As, Mn, Ni and Cr) 

since these metals are mostly, or entirely, in particulate form. However, mercury is different. 
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Mercury is emitted in three main forms (i.e., gaseous elemental mercury, gaseous oxidized 

mercury, and particulate bound mercury). We have no data regarding what percent of the 

mercury are in particulate versus gaseous forms for this source category. However, based on our 

knowledge and experience of mercury emissions from other industries, we believe a significant 

portion would be in the gaseous forms. Therefore, the mercury data collected for this source 

category, which is entirely based on baghouse dust samples, are not measurements of mercury

emissions since the mercury in the baghouse dust consists of the particulate bound mercury

portion only. The gaseous mercury emissions were not measured from any units. Therefore, there 

are significant uncertainties regarding the mercury emissions estimates for this source category. 

We used these limited baghouse dust mercury data to generate rough estimates of mercury

emissions for secondary aluminum sources for input to the risk modeling so that we could 

estimate the potential risks due to mercury emissions. Based on this approach, we estimated that 

the entire source category emits a total of less than one pound of mercury per year nationwide (as 

shown in table 3.1-1 of the risk assessment report). Nevertheless, these baghouse data and rough 

estimates of emissions are insufficient to establish emissions standards for mercury for this 

source category. Therefore, we are not promulgating emission standards for mercury as 

requested by the commenter at this time in this action. 

With regard to the other metal HAP and organic HAP, as mentioned above, the subpart RRR 

MACT standards have regulated those HAP since promulgation in 2000. The standards use PM 

as a surrogate to regulate the metal HAP (other than mercury) and THC as a surrogate to regulate 

non-D/F organic HAP. In addition, the 2000 rulemaking set separate MACT limits for D/F 

expressed as toxic equivalents and HCl as a surrogate for acid gases including HF, chlorine and 

fluorine, and in this rulemaking we are promulgating specific compliance provisions for HF, as 

discussed in the preambles to the proposed rules. Thus, the rule currently regulates all HAP 

known to be emitted from these facilities in measurable quantities.

1.2 Risk Assessment Methods

1.2.1 Modeling of MACT Allowable Emissions

Comment #1: Commenter 0287 recommended that the EPA consider potential or allowable 

emissions, rather than actual emissions, as much as possible in evaluating residual risk. The 

commenter stated that because facility emissions could increase over time for a variety of 

reasons, and with them the associated impacts, the use of potential or allowable emissions is 

more appropriate; an analysis based on actual emissions from a single point in time could 

underestimate the risk. The commenter stated that the major source HAP thresholds are based on 

maximum potential-to-emit, as opposed to actual emissions, and air agencies issue permits based 

on potential emissions. The commenter stated that limiting the scope of a risk evaluation to 

actual emissions would be inconsistent with the applicability section of part 63 rules. The 

commenter stated that they were pleased that the EPA used allowable emissions in parts of the 

rulemaking but were concerned that the EPA continues to use actual emissions in other parts of 

its assessment. The commenter encouraged the agency to use allowable emissions in the future, 

including in assessing acute health risks.

Response: Consistent with previous risk assessments, the EPA considers both allowable and 

actual emissions in assessing chronic exposure and risk under section 112(f)(2). See, e.g., 
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National Emission Standards for Coke Oven Batteries (70 FR 19998-19999, April 15, 2005); 

proposed and final National Emission Standards for Organic Hazardous Air Pollutants from the 

Synthetic Organic Chemical Manufacturing Industry (71 FR 34428, June 14, 2006, and 71 FR 

76603, December 21, 2006). This approach is both reasonable and consistent with the flexibility

inherent in the Benzene NESHAP framework for assessing ample margin of safety. As a general 

matter, modeling allowable emissions levels is inherently reasonable since this reflects the 

maximum level sources could emit and still comply with national emission standards. But it is 

also reasonable to consider actual emissions, where such data are available, in both steps of the 

risk analysis. See National Emission Standards for Coke Oven Batteries, 70 FR 19992, 19998 

(April 15, 2005). The chronic inhalation risk assessment for the secondary aluminum source 

category was conducted using actual and allowable emissions, and all of the results were 

considered in determining risk acceptability and ample margin of safety.

The commenter also urges the Agency to rely on allowable emissions for the purpose of our 

acute screening assessment. The use of allowable emissions was not considered in the acute 

assessment due to the conservative assumptions used to gauge worst-case potential acute health 

effects. The conservative assumptions built into the acute health risk screening analysis include: 

(1) use of peak 1-hour emissions that are on average ten times the annual average 1-hour 

emission rates; (2) that all emission points experience peak emissions concurrently; (3) worstcase meteorology (from 1 year of local meteorology); and (4) that a person is located downwind 

at the point of maximum impact during this same 1-hour period. Thus, performing an acute 

screen based on allowable emissions would be overly conservative and at best, of questionable 

utility to decision makers.

1.2.2 Modeling of Acute Exposure

Comment #1: One commenter (0193) noted that the EPA concludes that the acute level health 

risk from the secondary aluminum source category is within acceptable bounds, even after using 

worst case values for dose response, dispersion modeling, hourly maximum exposure location, 

meteorology and stationary out-of-doors human activity, which the commenter stated 

exaggerates risk. The commenter emphasized that the acute risk estimates the EPA calculates are 

the result of combined worst case assumptions, are very conservative and have a low probability

of occurring.

Response: The acute risk assessment is a screening-level assessment designed to identify

facilities and pollutants that need further analysis and can provide information for our risk-based 

decisions. The screen provides us information such that for those facilities where the hazard 

quotients are less than 1, we do not expect acute effects, and for those situations where the 

hazard quotients are greater than 1, the potential for acute effects may exist. For those situations 

where the acute hazard quotients are greater than 1 based on our screening assessment, the fact 

that it is a screening-level assessment is taken into consideration. A finding of unacceptable risks 

is not based on any one risk metric (e.g., acute hazard quotients), but rather considering all of the 

health and other information available and the degree of uncertainty associated with that 

information.

Comment #2: In a comment on the supplemental proposal, commenter 0287 stated that they 

have expressed their concerns in the past with the EPA’s use of Acute Exposure Guideline 
10

Levels (AEGLs) or Emergency Response Planning Guidelines (ERPGs) values to address acute 

exposures in the residual risk assessments and it appears the EPA is still using them for those 

purposes in this proposal. The commenter stated that in the December 2002 EPA document, "A 

Review of the Reference Dose and Reference Concentration Processes," the EPA stated that the 

primary purpose of the AEGL program is to develop guidelines for once-in-a-lifetime short-term 

exposures to airborne concentrations of acutely toxic chemicals; they are not meant to evaluate 

the acute impacts from routine emissions that occur over the life of a facility. The commenter 

stated that unlike the reference concentrations (RfCs) for chronic exposures, the AEGLs and 

ERPGs do not include adequate safety and uncertainty factors and cannot be relied upon to 

protect the public from the adverse effects of exposure to toxic air pollutants; the use of AEGLs 

or ERPGs in residual risk assessments is not appropriate and does not ensure that public health is 

adequately protected from the acute impacts of HAP exposure. The commenter stated that they

were gratified to see that the EPA has increased its reliance on the California Reference 

Exposure Levels (RELs) to address acute exposures in the residual risk assessments and continue 

to urge the EPA to use the RELs for these assessments.

Response: The EPA does not rely exclusively upon AEGL or ERPG values for assessment of 

acute exposures. Rather, the EPA’s approach is to consider various acute health effect reference 

values, including the California REL, in assessing the potential for risks from acute exposures. 

To better characterize the potential health risks associated with estimated acute exposures to 

HAP, and in response to a key recommendation from the SAB’s peer review of the EPA’s RTR 

risk assessment methodologies1, we generally examine a wider range of available acute health 

metrics (e.g., RELs, AEGLs) than we do for our chronic risk assessments. This is in response to 

the SAB’s acknowledgement that there are generally more data gaps and inconsistencies in acute 

reference values than there are in chronic reference values. In some cases, when Reference Value 

Arrays

2

for HAP have been developed, we consider additional acute values (i.e., occupational 

and international values) to provide a more complete risk characterization. As discussed in the 

preamble to the proposed rule (79 FR 72874), the exposure guidelines the EPA considers 

depends on which exposure guidelines are available for the various hazardous air pollutants 

emitted. The EPA uses AEGL and ERPG values (when available) in conjunction with REL

values (again, when available) to characterize potential acute health risks. However, it is often 

the case that HAP do not have all of these acute reference benchmark values. In these instances, 

the EPA describes the potential acute health risk in relation to the acute health values that are 

available. Importantly, when interpreting the results, we are careful to identify the benchmark 

being used and the health implications associated with any specific benchmark being exceeded.

 

1 The SAB peer review of RTR Risk Assessment Methodologies is available at: 

http://yosemite.epa.gov/sab/sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-007-

unsigned.pdf.

2 U.S. EPA. (2009) Chapter 2.9 Chemical Specific Reference Values for Formaldehyde in Graphical Arrays of 

Chemical-Specific Health Effect Reference Values for Inhalation Exposures (Final Report). U.S. Environmental 

Protection Agency, Washington, DC, EPA/600/R–09/061, and available on-line at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=211003.
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1.2.3 Multipathway Screening

Comment #1: One commenter (0193) stated that the EPA’s multi-pathway risk screening 

analysis combines multiple extreme assumptions and leads to an unrealistic estimate of risk. The 

commenter provided examples of the EPA’s assumptions and data inputs which the commenter 

believes exaggerate potential risks:

 The site modeled is a farm adjacent to a secondary aluminum facility, including an 

aquatic pond. All foods are consumed daily for the entire duration by the farm occupants 

locally from on-site, including all fish from the pond.

 Downwind air dispersion of HAP’s from the facility to the farm site and pond is assumed 

continuously using worst-case dispersion characteristics.

 Each person has an ingestion rate of food that exceeds expected body weight-normalized 

ingestion rates. In other words, all food stuffs are each consumed at a 90th percentile 

daily rate adding up to an enormous food intake rate per person. Fish consumption is all 

from the pond at the site, and the ingestion rate is assumed at the 99th percentile of daily

population intake.

 The ingestion of fish also includes the assumption that upper-trophic level fish (due to an 

absence of large-bodied herbivore/detritivore fish to favor higher concentrations of 

bioaccumulative chemicals) results in higher concentrations in consumed fish. The linear 

food-chain assumption further maximizes concentration of bioaccumulative chemicals in 

higher-trophic level fish.

 The lifetime risk calculation includes continuous ingestion and dermal exposure at the 

site, including all food originating from the site, 365 days per year.

 Individuals were assumed to be exposed on a fraction of their bodies (i.e., their head, 

forearms, hands, lower legs, and feet) to contaminated soil from the TRIM.FaTE surface 

soil parcel with the highest concentration (N1) on a daily basis. For the water evaluation, 

individuals were assumed to be exposed to contaminated surface water with the same 

PBHAP concentration as the TRIM.FaTE screening scenario pond over their entire 

bodies on a daily basis.

 All livestock feed is from the local farm site (including grains and silage) and are all 

derived from most highly impacted locations.

 A nursing mother is assumed to be continuously exposed to contaminants by all ingestion 

pathways modeled and can pass the contaminants on to her infant through breast milk, 

including dioxins and mercury.

The commenter noted that it is remotely possible that a small number of these ultra-upper-bound 

assumptions might occur at some site at some point of time, it is unrealistic to model all of these 

extreme assumptions simultaneously and continuously for any realistic assessment of risk. Given 

the exaggerated levels estimated in the analysis, the commenter stated that the EPA has reached a 
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reasonable conclusion with regard to the multi-pathway results. Beyond this conclusion, the 

commenter maintained, results of the multi-pathway analysis have no value and a more realistic 

and reasonable multi-pathway assessment would result in much lower risk estimates.

Response: The EPA originally developed the multipathway screening analysis to estimate worstcase non-inhalation exposures to PB-HAP. The approach uses numerous worst-case assumptions 

to ensure that exposure to PB-HAP is not underestimated. However since the time of proposal, 

the EPA has refined its emission screening thresholds for the multipathway analysis based on 

improved toxicity rating/scaling methods for POMs and dioxin congeners, as well as improved 

fate, transport, and uptake behavior through the aquatic food chain. We also expanded the 

multipathway analysis to include separate exposure scenarios, one for a subsistence fisher and 

one for a subsistence farmer. (See Appendix 4 of the risk assessment document for more details). 

Further, rather than using all worst-case meteorological and lake distance assumptions, we have 

incorporated more facility specific information into the multipathway screening scenarios. Given 

that it is highly unlikely that the most-exposed farmer is the same person as the most-exposed 

fisher, we consider these scenarios separately and do not consider it reasonable to add the risk 

results from these two exposure scenarios. While the screening analysis was not designed to 

produce a quantitative risk result, the factor by which the emissions exceed the threshold serves 

as a rough gauge of the “upper-limit” risks we would expect from a facility. Based on actual 

emissions from the secondary aluminum source category, facility-level emissions of POMs from 

all sources are below our revised multipathway screening threshold. With respect to dioxins, our 

revised multipathway screening threshold for cancer is exceeded by up to 70 times. None of the 

pollutants exceeded the chronic noncancer multipathway screening thresholds. Considering that 

these results are screening estimates that still incorporate a number of worst-case assumptions, it 

is likely that the actual multipathway cancer MIR and noncancer HQ values would be 

substantially less than 70-in-1-million and 1, respectively.

1.3 Uncertainties in Risk Assessment

Comment #1: One commenter (0193) stated that the EPA’s residual risk conclusions are 

reasonable; however the risk assessment calculations are likely to be substantial overestimations 

of the actual risk for secondary aluminum facilities. The commenter thought that each of these 

factors in and of themselves lead to an overestimation of risk, but when combined likely result in 

a synergistic impact leading to a much greater overestimation of risks. The commenter believes 

that the EPA’s risk evaluation demonstrates more than an ample margin of safety for the existing 

Secondary Aluminum NESHAP.

Response: Uncertainty and the potential for bias are inherent in all risk assessments, including 

those performed for this rulemaking. Although uncertainty exists, our approach, which uses 

conservative tools and assumptions, ensures that our decisions are appropriately health protective 

and environmentally protective. A brief discussion of the uncertainties in the RTR emissions 

datasets, dispersion modeling, inhalation exposure estimates and dose-response relationships can 

be found in the supplemental proposal for this rulemaking (79 FR 72874). A more thorough 

discussion of these uncertainties is included in the Residual Risk Assessment for the Secondary 

Aluminum Source Category in Support of the 2015 Risk and Technology Review Final Rule, 

which is available in the docket for this action.
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1.3.1 Individual Variability and Exposures

Comment #1: One commenter (0193) objected to the use of a safety factor of ten applied to the 

estimated hourly emissions maximum for short term acute health concerns such as for hydrogen 

chloride and hydrogen fluoride exposures. The commenter noted that the default value of ten is 

based on a study by the EPA of emissions in the Houston Texas area dominated by VOC 

emissions from petroleum and chemical operations that may not be representative of the 

emissions profile for hourly events in Secondary Aluminum. The commenter continued that a 

large uncertainty exists for evaluating acute risks, and the EPA has chosen a very conservative 

order-of-magnitude level safety margin in assessing acute exposure levels. The commenter stated 

that this level of conservatism will lead to a substantial overestimate of risk for acute exposures.

Response: This choice of a factor of ten for screening was originally based on engineering 

judgment. To develop a more robust peak-to-mean emissions factor, and in response to one of 

the key messages from the SAB consultation on our RTR Assessment Plan, we performed an 

analysis using a short-term emissions dataset from a number of sources located in Texas 

(originally reported by Allen et al. 2004). In that report, the Texas Environmental Research 

Consortium Project compared hourly and annual emissions data for volatile organic compounds

for all facilities in a heavily-industrialized 4-county area (Harris, Galveston, Chambers, and 

Brazoria Counties, TX) over an eleven-month time period in 2001. We obtained the dataset and 

performed our own analysis, focusing on sources which reported emitting high quantities of HAP 

over short periods of time (see Appendix 3, “Analysis of data on short-term emission rates 

relative to long-term emission rates”). Most peak emission events were less than twice the annual 

average, the highest was a factor of 74 times the annual average, and the 99th percentile ratio of 

peak hourly emission rate to the annual hourly emission rate was 9. Based on these results, we 

chose the factor of ten for all initial screening; it is intended to cover all possible hourly peaks

associated with routinely variable emissions. While there have been some documented emission 

excursions above this level, our analysis of the data from the Texas Environmental Research 

Consortium suggests that this factor should cover more than 99 percent of the short-term peak 

gaseous or volatile HAP emissions from typical industrial sources.

Thus, in the absence of source category-specific data or estimates, we use this default factor of 

10 in the acute health screen. We further note that the commenter did not provide specific 

evidence that the acute factor of 10 is inappropriate for this source category, nor did the 

commenter suggest a different acute screening factor. However, even using this factor of 10, the 

potential for acute health risks from this source category was negligible.

Comment #2: One commenter (0193) asserted that the omission of a mobility/activity analysis 

is estimated by the EPA to overestimate risk by 25 percent for particulate HAPS (such as metals) 

based only on short-term mobility patterns, but the inclusion of long-term activity patterns, such 

as moving residences and job locations, would result in even lower risk estimates.

The commenter noted that another omission resulting in over estimation is consideration of 

indoor versus outdoor exposures in the assessment. The commenter argued that for particulate 

types of emissions the difference is significant, noting that the EPA estimates that indoor 
14

exposures for particulate types of emissions may be reduced by a value of 25 to 30 percent. The 

commenter concludes that the risks projected for metals and dioxin emissions are also 

additionally overestimated by a factor of 25 to 30 percent. 

The commenter maintained that combined with the mobility pattern issue impacts on risk, 

chronic individual and population risks from these factors are likely overestimated by an 

additional factor of two.

The commenter also argued that the EPA’s omission of population mobility will bias the risk 

estimate for cancer incidence, as there is continued scientific interest in using a non-linear doseresponse modeling approach for dioxin compounds.

Response: In general, we strive to strike a balance in our assessments, meaning that while some 

factors likely lead to overestimates of risk (e.g., 70-year exposure duration), others likely lead to 

underestimates of risk (e.g., building downwash not modeled). We conclude that the risk 

assessment for this source category is sufficient to support decisions on the acceptability of the 

risk and ample margin of safety. 

The commenter is correct that the EPA did not consider short-term or long-term mobility in the 

assessment. Mobility was not considered because we do not believe that assumption, in 

combination with other modeling assumptions, leads to a significant bias in the risk results in any

one direction. For example, the EPA does not consider that homes and businesses may locate 

closer to facilities over time, which could lead to an underestimation of risk. Additionally, 

estimates of the maximum individual risk (MIR) contain uncertainty, because they are derived at 

census block centroid locations rather than actual residences. This uncertainty is known to create 

potential underestimates and overestimates of the actual MIR values for individual facilities, but 

overall, we believe it does not have a significant impact on the estimated MIR for a source 

category. Processes like deposition, plume depletion, and atmospheric degradation are not 

considered, which may introduce bias to the population exposure estimates. Finally, we did not 

factor in the possibility of a source closure occurring during the 70-year chronic exposure period, 

leading to a potential upward bias in both the MIR and population risk estimates; nor did we 

factor in the possibility of population growth during the 70-year chronic exposure period, leading 

to a potential downward bias in both the MIR and population risk estimates. These uncertainties 

are described in section 4.1 of the risk assessment document.

In assessing risk, we estimate the MIR or the maximum HI, which are defined as the risk (or 

hazard) associated with a lifetime of exposure at the highest concentration where we determine 

people may actually reside. For this assessment, we used the annual average ambient air 

concentration of each HAP at each census block centroid as a surrogate for the lifetime 

inhalation exposure concentration of all the people who reside in the census block. Basing 

exposure estimates at census block centroids may underestimate or overestimate actual exposure 

concentrations at some residences, as discussed in the response below. Further reducing exposure 

estimates for the most highly exposed residents by modeling their short-term behavior could add 

a systematic low bias to these results and is not expected to affect the MIR result. Thus, this risk 

analysis did not consider the short-term human activity patterns and their potential influence on 
15

exposure. Our experience with the National-Scale Air Toxics Assessments (NATA)3(which 

modeled daily activity using the EPA’s HAPEM model) suggests that, given our current 

understanding of microenvironment concentrations and daily activities, modeling short-term 

activity would, on average, reduce risk estimates about 25 percent for particulate HAP; it would

also reduce risk estimates for gaseous HAP, but typically by much less. 

We acknowledge that our assumption that people may be present at their homes for 24 hours per 

day over a 70-year lifetime represents a scenario that likely overestimates the actual exposures 

received by people living near the facilities. Most people have daily activities that take them to 

areas where exposure concentrations are different and people may move to new residences 

periodically. Both of these behaviors will likely tend to lower lifetime exposures and, therefore, 

risk if they are no longer in the vicinity of sources in the source category. 

In our risk assessments, we estimate risk for the “maximum individual risk” (MIR) which is 

different than the “maximum exposed individual (MEI).” The MEI could be equal to or greater 

than the MIR as the MEI is the highest estimated risk to a hypothetical exposed individual, 

regardless of whether people are expected to occupy that area. The MIR, on the other hand, is the 

highest estimated risk to an exposed individual in areas people may actually occupy. We are 

using the MIR to be considered equivalent to the “individual most exposed” phrase from the 

CAA section 112(f)(2). This approach is consistent with the Commission on Risk Assessment 

and Risk Management report recommendation that exposure assessments should not be based on 

a hypothetical MEI.

Comment #3: In a comment on the supplemental proposal, commenter 0287 stated that in using 

long-term concentrations affecting the most highly exposed census block for each facility, the 

EPA's analysis dilutes the effect of sources’ emissions by estimating the impact at the centroid of 

the census block instead of at the property line or wherever the maximum exposed individual is

located. The commenter stated that census blocks can be large geographically, depending on the 

population density, so the maximum point of impact can be far from the centroid, including at or 

near the property line where people may live or work; the EPA itself alludes to this problem in 

the preamble. The commenter stated that even if the area near the property line is not developed, 

over time homes and businesses could locate closer to the facility. The commenter stated that 

while it is possible that population distribution is homogenous over a census block, this 

assumption is not necessarily accurate in considering the predicted impacts from the location of a 

source; using HEM-3, the EPA can identify the maximum individual risk at any point in a census 

block that is within a 50-kilometer radius from the center of the modeled facility. The commenter 

stated that based on HEM-3’s power and ability, they suggest that the EPA abandon its use of the 

predicted chronic exposures at the census block centroid as surrogates for the exposure 

concentrations for all people living in that block; rather, they recommended that the EPA use the 

truly maximum individual risk, irrespective of its location in the census block.

Response: In a national-scale assessment of lifetime inhalation exposures and health risks from 

facilities in a source category, it is appropriate to identify exposure locations where it may be 

reasonably expected that an individual will spend a majority of his or her lifetime. In determining 

chronic risks, it is appropriate to use census block information on where people actually reside, 

 

3 www.epa.gov/nata
16

rather than points at the property line, to locate the estimation of exposures and risks to 

individuals living near such facilities. Census blocks are the finest resolution available as part of 

the nationwide population data (as developed by the US Census Bureau); on average, a census 

block is comprised of approximately 40 people and about 10 households. In the EPA risk 

assessments, the geographic centroid of each census block containing at least one person is used 

to represent the location where all the people in that census block live. The census block centroid 

with the highest estimated exposure then becomes the location of maximum exposure, and the 

entire population of that census block is assumed to experience the maximum individual risk. In

some cases, because actual residence locations may be closer to or farther from facility emission 

points, this may result in an overestimate or underestimate of the actual annual concentrations 

(although there is no systematic bias for average levels). Given the relatively small dimensions 

of census block in densely-populated areas, there is little uncertainty introduced by using the 

census block centroids in lieu of actual residence locations. There is the potential for more 

uncertainty when the census block are larger, although there is still no systematic bias. The EPA 

concludes that the most appropriate locations at which to estimate chronic exposures and risks 

are the census block centroids because: 1) census blocks are the finest resolution available in the 

national census data; 2) facility fence lines do not typically represent locations where chronic 

exposures are likely (i.e., people do not typically live at the fence line of facilities); and 3) there 

is no bias introduced into the estimate of the maximum individual risk (MIR) by using census 

block centroid locations. In its peer review of the methodologies used to estimate risks as part of 

the RTR rulemaking efforts, the EPA’s Science Advisory Board (SAB) endorsed this approach. 

In addition to the approach described above, the EPA recognizes that where a census block 

centroid is located on industrial property or is large and the centroid is less likely to be 

representative of the block’s residential locations, the block centroid may not be the appropriate 

surrogate. For this source category, as described in the risk assessment document available in the 

docket, in cases where a census block centroid was within 300 meters of any emission source 

(and therefore possible on facility property), we viewed aerial images of the facility to determine 

whether the block centroid was likely located on facility property. Likewise, we examined aerial 

image of all large census blocks within one kilometer of any emission source. If the block 

centroid did not represent the residential locations within that block, we relocated it to better 

represent them and/or we added receptors for residences nearer to the facility than the centroid.

For this source category, we added several receptors for census blocks where the centroid 

location was not representative of the residential locations. Appendix 7 of the risk assessment, 

entitled Residual Risk Assessment for the Secondary Aluminum Production Source Category in 

Support of the 2015 Risk and Technology Review Final Rule provide additional information on 

these changes.

In assessing risk, we estimate the MIR, which is defined as the risk associated with a lifetime of 

exposure at the highest concentration where we determine people may actually reside. For this 

assessment, we used the annual average ambient air concentration of each HAP at each census 

block centroid as a surrogate for the lifetime inhalation exposure concentration of all the people 

who reside in the census block. Basing exposure estimates at census block centroids may

underestimate or overestimate actual exposure concentration at some residences. Further 

reducing exposure estimates for the most highly exposed residents by modeling their short-term 

behavior could add a systematic low bias to these results and is not expected to affect the MIR 

results. Thus, this risk analysis did not consider the short-term human activity patterns and their 
17

potential influence on exposure. Our experience with the EPA’s National-Scale Air Toxics 

Assessment (NATA) (which model daily activity using the EPA’s HAPEM model) suggests that, 

given our current understanding of microenvironment concentrations and daily activities, 

modeling short-term activity would, on average, reduce risk estimates about 25 percent for 

particulate HAPs; it would reduce risk estimates for gaseous HAPs, but typically by much less.

Comment #4: In a comment on the supplemental proposal, commenter 0287 stated that in 

considering environmental justice issues, improvements are needed in the EPA’s methods of 

evaluating environmental justice and encouraged the EPA to continue to consider these factors in 

developing the final rule and subsequent regulations. The commenter recommended that the EPA 

conduct the demographic analysis on individuals projected to experience a risk greater than 1-in1-million and also on individuals living within five kilometers of the facility, regardless of 

projected risk, consistent with the approach used for the Hard and Decorative Chromium 

Electroplating and Chromium Anodizing Tanks source category. The commenter stated that the 

socio-economic analysis for this rule did not evaluate potential disparities within five kilometers 

for cancer risk at maximum allowable emission levels; this type of analysis is especially 

important in instances where a facility is located in a minority and low-income community. The 

commenter stated that the EPA only evaluated the risk to the population within a 50-kilometer 

radius, which could dilute the results by including populations not in the demographic groups 

most at risk. The commenter stated that this is especially the case if the source is located in or 

next to a minority or low-income population. The commenter recommended that an analysis at 

the five-kilometer distance be conducted to assess facility impacts to nearby environmental 

justice communities and that the rule writers work with the EPA Office of Environmental Justice 

to develop criteria and specific guidance on how to interpret and apply the outcome of these 

types of analyses in the rulemaking process.

Response: The commenter is correct that we performed the demographic analyses for the 

Secondary Aluminum source category differently than we did for the October 2010 proposed 

RTR for the chrome electroplating and anodizing source categories (75 FR 65067, October 21, 

2010). We performed the demographic analyses for the chrome source categories using two 

approaches as examples of how such analyses might be developed, and invited public comment 

on the approaches used and the interpretations made from the results. In the first approach, we 

focused the analysis on the total populations residing within 5 km of each facility, regardless of 

their estimated risks, and examined the distributions across various demographic groups within 

those 5 km circles. That analysis was a “proximity” analysis in that it considered only the 

distance from the emission sources to surrounding populations, and not the estimated risks to 

those populations

In the second approach, we focused the analysis on the populations within 5 km of any facility

estimated to have exposures to HAP which result in cancer risks of 1-in-1 million or greater or 

non-cancer hazard indices of 1 or greater. We examined the distributions of those risks across 

various demographic groups. In each approach, we compared the percentages of particular 

demographic groups to the total number of people in those demographic groups nationwide. We 

stated in the proposed rule for the chrome source categories that in future rules we planned to 

extend the analyses to cover the entire modeled domain for a facility (50 km radius) to capture 

all individuals with risks above 1-in-1 million or greater or non-cancer hazard indices of 1 or 
18

greater. We also stated that generally we have found that using a 5 km radius in the analysis will 

capture more than 90 percent of the individuals with cancer risks above 1-in-1 million.

In the February 2012 supplemental proposal for the RTR for the chrome source categories, our 

demographic analyses included populations within 50 km of each source (including those very

near the sources) with risks of 1-in-1 million or greater or non-cancer hazard indices of 1 or 

greater (77 FR 6628, Feb. 8, 2012). We did not include analyses using a 5 km radius in that 

supplemental proposal. We believe that, where a risk assessment has been performed, it is more 

informative to consider the demographics of all populations (including those beyond 5 km) with 

elevated risks than to limit the demographics analysis to populations located within 5 km of a 

facility. Where a risk assessment has been performed, these populations are identified, and the 

source parameters such as low release height are taken into account. As discussed above, we 

have found that most exposure locations with the highest estimated risks are within 5 km of a 

facility, so extending the radius to 50 km has little impact on an analysis based on risks, but 

makes more sense because 50 km corresponds to the risk modeling radius and includes all 

populations with elevated risk estimates. We also note that we are working with the Office of 

Environmental Justice to implement the latest guidance, issued May 29, 2015, as appropriate, to 

ensure that environmental justice issues are being considered in the rulemaking process.

Comment #5: One commenter (0193) argued against the EPA’s use of the upper bound 

estimates for dioxin related risk, and stated that given the wide-spread and common occurrence 

of dioxin and furans in nature, it is not likely that there are no defense mechanisms in the human 

body to protect against dioxin impacts, and it is unlikely that low dose exposures are as potent, 

molecule-for-molecule, as high dose exposures. The commenter concluded that the EPA doseresponse model is likely to be a conservative overestimate of risks, especially at low exposure 

levels, but the quantification of the overestimate is not possible at this time.

The commenter cited several statements from the SAB Dioxin Review Panel concerning the 

need for nonlinear and linear methods for characterizing cancer risk which the commenter 

asserted indicate that the EPA’s assumption of no-threshold linearity in the dioxin dose-response 

curve is likely to be most conservative and may overestimate risk substantially, especially at low 

dose levels.

Response: We disagree that the EPA should consider that the human body has natural defense 

mechanisms against health effects associated with dioxin exposure and note that the commenter 

provided no evidence in support of such assertions. In general the development of UREs and 

RFCs consider results from animal toxicological studies and/or human studies where an effect 

has been observed notwithstanding whatever natural defenses (if any) from HAP may be present 

in the species tested. Furthermore, the commenter provided no evidence for its conclusion that it 

is unlikely that low dose exposures are as potent as high dose exposures.

With respect to model use, the EPA’s long standing science policy approach has been to use 

linear low-dose extrapolation as a default option for carcinogens for which the mode of action 

(MOA) has not been identified. We expect future EPA dose-response assessments may identify

nonlinear MOAs and we intend to use those analyses, as appropriate, in our risk assessments. At 
19

this time, however, there is no available carcinogen dose-response assessment for inhalation 

exposure to dioxin that is based on a nonlinear MOA. 

Comment #6: One commenter (0193) disagreed with the EPA’s assumption of a 70 year lifetime 

calculation for exposures to HAPs in the risk analysis, and the EPA’s assumption that facilities 

will not experience partial or full curtailments of operations, asserting that this leads to additional 

overestimates of long term cumulative risk estimates. The commenter pointed out that over the 

last two decades, many Secondary Aluminum plants have been shut-down or experienced short 

and multi-year curtailments, leading to overestimation of cumulative risks.

Response: The commenter is correct that the EPA assumes no curtailment of operations over the 

70 year chronic exposure period. In assessing risk, we estimate the maximum individual risk 

(MIR) or the maximum hazard index (HI), which are defined as the risk (or hazard) associated 

with a lifetime of exposure at the highest concentration. For this assessment, we used the annual 

average ambient air concentration of each HAP at each census block centroid as a surrogate for 

the lifetime inhalation exposure concentration of all the people who reside in the census block. 

Basing exposure estimates at census block centroids may underestimate or overestimate actual 

exposure concentrations at some residences. The risk assessment also contains other assumptions 

that could lead to an underestimation or overestimation of risk; for example the assessment does 

not take into account population growth or human activity patterns over the 70 year period.

1.4 Risk Assessment Results

Comment #1: One commenter (0189) expressed support for the proposed amendments, stating 

that the emission standards proposed in this amendment will adequately protect the environment 

and communities close to Secondary Aluminum Production facilities, although the commenter 

also offered suggestions for the proposed rule (addressed elsewhere in this document or the 

preamble to the final rule).

Response: The EPA acknowledges the commenter’s support.

Comment #2: In a comment on the supplemental proposal, commenter 0290 stated that they

support The Aluminum Association’s (TAA) comments asserting that the EPA’s risk estimates 

are generally overestimated for hazardous air pollutant (HAP) emissions from secondary

aluminum facilities because the EPA bases it calculations on unreasonable and overly 

conservative worst-case risk assumptions.

In a comment on the supplemental proposal, commenter 0295 stated that they support the EPA's 

finding of acceptable risks but believes that the EPA risk estimates are generally overestimated. 

The commenter stated that each of the factors assessed by the EPA in their risk assessment, 

including emissions, population location and exposures, multi-pathway exposures, and the dose 

response and health risk values of the emitted pollutants of concern, includes uncertainties that

the EPA addresses in the preamble. The commenter stated that generally, the EPA addresses 

uncertainties by biasing the analysis high using a worst-case upper bound risk preference; the 

EPA also assesses ample margin of safety to provide risk protection as mandated under the CAA. 

The commenter stated that several key high-bias risk assumptions combine to make the estimates 

of risk high and well above actual risks likely to occur. The commenter concluded that the 
20

current MACT emission limits provide more than an ample margin of safety, including 

emissions from co-located facility-wide operations. The commenter stated that the factors that 

lead to this conclusion include:

 The determination of hourly emissions estimates based on annual emission rates,

 The decision not to address individual or population mobility, including long and short 

term activity patterns and indoor exposure differentials,

 The assumption of 70 year lifetime risk assuming no facility shutdowns, partial 

curtailments or other reductions in emissions that may occur,

 The conservative nature of the dose-response especially for D/F speciation that rely on 

unit risk estimates derived from the multi-stage single-hit no threshold models for 

calculating carcinogenic risk,

 For acute health concerns, the combined assumptions of worst case dose-response, worst 

case dispersion modeling, worst case hourly maximum exposure location, worst case 

meteorology and worst case stationary human activity,

 For the multi-pathway analysis, a combination of implausible assumptions for 

exposure/ingestion rates coupled with unlikely food source scenarios.

Response: Uncertainty and the potential for bias are inherent in all risk assessments, including 

those performed for this rulemaking. Although uncertainty exists, our approach, which used 

conservative tools and assumptions, ensures that our decisions are appropriately health protective 

and environmentally protective. We disagree with the commenter that the EPA’s risk estimates 

are based on “unreasonable and overly conservative worst-case risk assumptions.” A brief 

discussion of the uncertainties in the RTR emissions datasets, dispersion modeling, inhalation 

exposure estimates and dose-response relationships can be found in the proposal for this 

rulemaking (79 FR 72874). A more thorough discussion of these uncertainties is included in the 

Residual Risk Assessment for the Secondary Aluminum Production Source Category in Support 

of the August 2015 Risk and Technology Review Final Rule, which is available in the docket for 

this action.

Comment #3: In a comment on the supplemental proposal, commenters 0294 and 0296 stated 

that they believe that the EPA’s conclusions regarding residual risk for the Secondary Aluminum 

source category are appropriate and they supported the Agency’s proposed findings.

Response: The EPA acknowledges the commenter’s support.
21

2. Rule Provision Changes

2.1 Control Device Shutdown

Comment #1: Commenters (0192, 0193, 199) disagreed with the EPA’s proposal to require a 

period of 24 hours before controls can be turned off on idled furnaces. 

Commenter 0192 stated that in batch-operated furnaces emissions stop once operations end, and 

that different furnaces have different emission characteristics so the shutdown sequence should 

be specified in the OM&M Plan.

Commenter 0193 argued that there is no reason to wait 24 hours to shut down APCD if a furnace 

is not operating. The commenter asserted that this is an unreasonable and unnecessary new 

restriction. The commenter proposed that the EPA allow controls to be turned off immediately 

after completion of the cycle, as there will be no emissions present and, further, that the EPA add 

the following new provision:

The owner or operator of a new or existing affected source that meets the following criteria may

temporarily turn off associated fans, hoods, and APCD. During the idle period, the source will:

 Only burn clean fuel

 Not receive new charge, flux or alloying material 

 Before charging resumes, all associated fans, hoods and APCD must be turned on and 

operated continuously.

Facilities should also be allowed to turn off controls, without idling for 24 hours. The following 

reasons are examples:

 If a bag leak detection system (BLDS) alarm sounds and inspection requires entry into 

the baghouse to conduct a bag leak check.

 Additionally, if a source is going to do a routine internal baghouse inspection, the 

proposed change would require the furnace be idled 24 hours prior to this so the 

baghouse can be shut down.

 Finally, if a source is going to a complete bag change, the proposed change would add 24 

hours of idle time before the baghouse can be shut off.

Commenter 0199 suggested the following rule language:

"The owner or operator of a new or existing affected source that will be idle for at 

least 24 hours and will burn clean fuel only, and will not receive new charge, flux 

or alloying material, may immediately upon idling the source, temporarily turn off 

associated fans, hoods and any APCD. Before charging resumes, all associated 

fans, hoods and APCD must be turned on and operated continuously. "
22

Response: The commenters misinterpreted the proposed rule. The proposed rule did not require 

a furnace to be shut down for 24 hours before a control device can be turned off. The provision 

as finalized applies to “natural gas-fired, propane-fired or electrically heated group 1 furnaces 

that will be idled for at least 24 hours...” and allows associated capture and collection system

fans and APCD to be temporarily turned off so long as the furnace will not receive new 

feed/charge, flux or alloying material. See 40 CFR 63.1506(m)(7) and Table 2 to Subpart RRR.

Nor does the final rule require owners or operators to wait 24 hours before turning off a 

baghouse to respond to a bag leak detection system alarm, conduct a routine baghouse 

inspection, or conduct a change out of bags in a baghouse. The EPA’s goal, as stated in the 

preamble to the proposed rule, is to allow owner/operators to turn off control devices for 

furnaces that will be shut down for extended periods, such as a weekend. The final regulation in 

40 CFR 63.1506(m)(7) and Table 2 makes clear that if a furnace will be idled for at least 24 

hours after the end of a cycle, then the associated capture and collection systems and APCD may 

be temporarily turned off. The rule also makes clear that before charging resumes, all associated 

capture and collection systems and APCD must be turned on and operated continuously.

Comment #2: One commenter (0189) noted that there are a variety of reasons, such as ordinary 

maintenance or market material issues, when there could be periods shorter than twenty-four (24) 

hours when the furnace could shut down or remain idle and not be charged with aluminum 

and/or fluxing. The commenter suggested that instead of allowing facilities to discontinue use of 

control devices only after remaining idle after a twenty-four hour period, the commenter 

proposed a thirty (30) minute time frame after the charge area is emptied and melting has 

completed. 

Response: As discussed in the preceding response, the regulation does not require a furnace to 

be shut down for 24 hours before a control device can be turned off. The purpose of this rule 

change is to allow facilities with furnaces that will be idle over a weekend, or other period 

exceeding 24 hours to discontinue use of control devices while the furnace is idle. The purpose 

of the rule change is not to allow control devices to be shut down if the furnace is idle for shorter 

periods of time. The EPA believes the added flexibility provided by the rule change will 

accommodate most situations identified by industry while balancing the need to practically and 

effectively enforce the emission control requirements of subpart RRR. In the EPA’s experience, 

if control systems and devices for furnaces were allowed to be temporarily turned off for short 

time periods (i.e., less than 24 hours) based on the furnace being “idle” it would be difficult for a 

compliance inspector to retroactively confirm with certainty that capture and collection systems 

and APCD were being operated as required to achieve continuous compliance with emission 

standards and were being turned off only as permitted. The EPA has clarified in the final rule

that use of control devices can be discontinued after the furnace cycle has been completed, if the 

furnace will remain idle for at least 24 hours.

2.2 Change of Furnace Classification

Comment #1: Commenters (0192, 0193) disagreed with requirements of §63.1514(c) for 

furnaces changing to from group 1 to group 2. The commenter stated that the EPA has provided 
23

no basis for reducing the limits or for requiring performance tests for group 2 furnaces, which, 

according to the commenter, have no potential for significant HAP emissions. 

Response: The original subpart RRR MACT rule subcategorized furnaces into group 1 and 

group 2 based on the difference in HAP emission potential from the materials melted (non-clean 

charge v. clean charge) and the type and amount of flux added (lack or presence of reactive flux).

See 64 FR 6946, 6960 (February 11, 1999) (proposed rule). A group 2 furnace is defined as a 

furnace that melts, holds, or processes only clean charge and that performs no fluxing or 

performs fluxing using only nonreactive, non-HAP-containing/non-HAP-generating gases or 

agents. We defined and exempted group 2 furnaces from subpart RRR numerical MACT 

emission standards in part on the basis that they are clean and emit little or no HAP emissions; 

instead, we required work practice procedures under section 112(h). Id. at 6961. Although group

2 furnaces generally are not subject to numerical emission standards under subpart RRR, the 

EPA believes it is appropriate to require a furnace that seeks to change from group 1 to group 2, 

and therefore will no longer be subject to numerical group 1 emission standards, to demonstrate 

based on performance testing that it qualifies as a group 2 furnace. Unlike other group 2 

furnaces, these furnaces were allowed to operate as group 1 furnaces without being restricted to 

clean charge and no reactive flux. The EPA is requiring these furnaces to demonstrate that they

can operate within the emission profile of a group 2, rather than group 1, furnace. The EPA 

proposed specific emission levels for this purpose and received no comments that served to alter 

the proposed emission levels, and we are adopting them in the final rule as proposed. We note 

that the commenter did not submit any testing or other emissions information to document its 

assertion concerning the potential for HAP emissions. We also note that in the absence of a 

performance test requirement to confirm the low level of emissions of furnaces changing from 

group 1 to group 2, the EPA might consider whether allowing such changes is appropriate or 

whether its regulatory approach to group 2 furnaces should be reviewed.

Comment #2: Commenters (0192, 0199) objected to the requirements of §63.1514(d) for 

area sources to repeat testing every 5 years, as they are contrary to the requirements 

developed by the EPA that one-time testing was sufficient for area sources after a 

detailed evaluation for the 2000 NESHAP. The commenter asserted that since the 

original NESHAP included the ability to change operating modes there is nothing about 

changing modes that changes that situation. The commenter claimed that the EPA 

provides no basis in the proposed rule for imposing the burden of repeat testing on area 

sources.

Response: We did not intend for area sources to repeat testing every 5 years under the change of 

classification provisions, and we have made it clear in the final rule that area sources are not 

required to repeat testing every 5 years.

Comment #3: In a comment on the supplemental proposal, commenter 0294 stated that the 

proposed limit at Section 63.1514(e) allowing four furnace operating mode changes in any 6-

month period, with the ability of sources to apply to the permitting authority for additional 

furnace operating mode changes, is appropriate.

In a comment on the supplemental proposal, commenter 0295 stated that while they objected in 

their comments on the 2012 proposal to the restrictions proposed for changing furnace 
24

classification, given the analysis provided in the supplemental proposal indicating that limited 

changes actually occur, and the EPA’s proposal to allow furnace operating mode changes no 

more than 4 times in a 6-month period, or to obtain prior approval from the permitting authority 

if additional changes are needed, the requirements appear reasonable.

Response: The EPA acknowledges the commenters’ support of the rule requirements on the 

frequency of switching furnace operating modes.

Comment #4: One commenter (0194) recommended that the EPA delete the parameter for 

“throughput” in §§63.1514(c)(1)(ii), (c)(3)(ii), (d)(1)(i) and (d)(2)(ii), and the requirement to 

establish a performance testing parameter. The commenter observed that this requirement is not 

necessary as emission limits under the rule are already normalized to process throughput (i.e., 

lb/ton).

Response: To ensure that any furnace that is changing its classification or operating 

mode is subject to the same testing requirements that apply to all furnaces at secondary

aluminum production facilities, specific performance testing and compliance 

demonstration requirements, for example the requirement to establish process throughput 

or lime injection rates, have been removed from section 63.1514 in the final rule. Instead, 

section 63.1514 of the final rule requires that operating parameters be established in 

accordance with the performance testing and compliance demonstration requirements in 

sections 63.1511 and 63.1512.

Comment #5: One commenter (0194) stated that the requirements in Sections 63.1514(c)(1) and 

(d)(1) should be clarified to state that only uncontrolled group 1 furnaces must conduct 

performance testing for HF.

Response: The commenter is correct in that HF testing is only required for uncontrolled4group 1 

furnaces, and Section 63.1514 is revised accordingly in the final rule.

Comment #6: One commenter (0194) stated that §§63.1514(a)(1)(ii), (a)(2)(iii), (a)(3)(ii), 

(a)(4)(iii), (a)(6)(iii), (b)(1)(ii), (b)(2)(iii) (b)(3)(ii), (b)(4)(iii), (b)(6)(iii), (c)(1)(ii), (c)(3)(ii) and 

(d)(1)(i) require the establishment of a “flux” rate parameter during performance testing, but it 

does not consider the fact that some group 1 furnaces do not flux. The commenter recommended 

that references to establishing a “flux rate” parameter during performance testing should be 

qualified to state “where applicable.”

Response: In the final rule, as discussed above, the change of furnace classification provisions 

do not list monitoring and operating parameters that must be established; instead, the provision 

requires that the parameters be established in accordance with §63.1511(g).

Comment #7: One commenter (0194) noted that §§ 63.1514(a)(1)(ii), (a)(3)(ii), (a)(5)(iii), 

(b)(1)(ii), (b)(3)(iii), (b)(5)(iii), (c)(1)(ii), (c)(3)(ii) and (d)(1)(i) require the establishment of a 

“lime injection” parameter during furnace testing. The commenter observed that some baghouses 

used to control emissions from Subpart RRR regulated group 1 furnaces are not lime-injected, 

 

4 Here and throughout the rest of this document, “uncontrolled” is used to indicate an emission unit, such as a group 

1 furnace, that is not controlled by an add-on air pollution control device.
25

and the reference to establishing a “lime injection” parameter should be qualified to state “where 

applicable.”

Response: In the final rule as discussed above, the change of furnace classification provisions do 

not list parameters that must be established; instead, the provisions require that operating 

parameters be established in accordance with §63.1511(g).

Comment #8: One commenter (0194) recommended that the performance test language 

throughout §63.1514 should be revised to match §63.1511(b)(1) of the current Subpart RRR 

rule:

“The owner or operator must conduct each test while the affected source or 

emission unit is operating at the highest production level with charge materials 

representative of the range of materials processed by the unit and, if applicable, at 

the highest reactive fluxing rate.”

One commenter (0199) asserted that in paragraph §63.1514(a)(l)(i), the EPA should clarify that 

highest throughput expected means throughput for the scrap chosen for the test, and that the 

scrap should be the worst-case material likely to be processed in the affected source.

One commenter (0199) stated that in paragraphs §63.1514(b)(l)(i), §63.1514(c)(l)(i), 

§63.1514(c)(3)(i), §63.1514(d)(1)(i), and §63.1514(d)(2)(i), regarding the rule text, “The 

performance test must be conducted with the scrap containing the highest level of contamination 

expected to be processed, at the highest throughput expected and using the highest rate of 

reactive flux injection expected ...” the EPA should clarify that these worst-case charge 

materials, and blends of these, have differing process rates and, therefore, the charge rate from 

the stack tests is not representative of the production rate that will be achieved during normal 

operations. 

The commenter (0199) disagreed with wording in paragraphs §63.1514(c)(1)(ii), 

§63.1514(c)(3)(ii) and §63.1514(d)(l)(i), “Parameters for throughput, capture, flux rate, and lime 

injection must be established during these tests,” stating that throughput should not be included 

as a parameter. The commenter asserted that because the test requires "scrap containing the 

highest level of contamination expected to be processed ... " throughput should not be 

determined when running worst case materials.

Response: As discussed in the 2014 supplemental proposal (79 FR at 72902) and in section 3.2 

of this document, we are clarifying the requirements for conditions under which performance 

tests for group 1 furnaces must be conducted. As provided in the final rule at 40 CFR 

63.1511(b)(1), testing must be conducted “under representative conditions expected to produce 

the highest level of HAP emissions ... (considering the extent of scrap contamination, reactive 

flux addition rate and feed/charge rate).” If a single test condition is not expected to produce the 

highest level of emissions for all HAP, “testing under two or more sets of conditions (for 

example high contamination at low feed/charge rate, and low contamination at high feed/charge 

rate) may be required.” Id. Regarding the establishment of operating parameter values used to 

monitor compliance, the final rule requires that those parameters be established as part of 
26

changing furnace classification in accordance with the section 63.1511(g) requirements for the 

establishment of monitoring and operating parameter values.

Comment #9: One commenter (0194) recommended that the EPA either delete the requirement 

to establish “parameters for capture” in paragraphs §§63.1514(a), (b) and (c) or provide detailed 

clarification on the specific parameters an owner or operator must establish for capture and then 

allow the aluminum industry an opportunity to comment on these specific requirements.

One commenter (0199) stated that in paragraphs §63.1514(a)(l)(ii), §63.1514 (a)(3 )(ii), 

§63.1514 (a)(4)(iii), §63.1514 (b)(1)(ii), §63.1514 (b)(2)(iii), §63.1514 (b)(3)(ii), §63.1514 

(c)(1)(ii), §63.1514 (d)(l )(i), and §63.1514 (d)(2 )(iii), the EPA has not defined the term 

"capture" or what qualifies as a parameter suitable to meet this requirement. The commenter 

asked that the EPA define what is an acceptable capture parameter. The commenter stated that 

baghouse flow rate, baghouse pressure drop, or baghouse fan RPM are appropriate to be included 

as in such a definition of a capture parameter. The commenter also asked that the EPA make 

certain that it provide for alternative parameters to be used as appropriate.

Commenter (0197) recommended that the EPA should clarify the definition of a Capture and 

Collection System to read “systems including duct systems and fans and in some cases, hoods” 

to allow for a capture and collection system that does not have a hood. 

Response: To ensure that any furnace that is changing its classification or operating mode is 

subject to the same testing and compliance requirements that apply to the relevant classification 

of furnaces, specific performance testing and compliance demonstration requirements, including 

parameters for capture, have been removed from section 63.1514 in the final rule. Instead, 

section 63.1514 of the final rule requires that operating parameters be established in accordance 

with the performance testing and compliance demonstration requirements in sections 63.1511

and 63.1512. Specifically, in the final rule, furnaces that change their operating mode, like all 

furnaces subject to subpart RRR requirements, are subject to the applicable requirements for 

capture and collection systems in section 63.1506(c), the monitoring requirements for capture 

and collection systems in section 63.1510(d) as well as the testing requirements in section 

63.1512, including the requirements for testing uncontrolled furnaces. We agree with the 

commenter’s suggestion to modify the definition of “capture and collection system” to account 

for those systems that do not have a hood and the definition in the final rule reflects that change.

Comment #10: One commenter (0199) suggested that §63.1514(a)(6)(i) and §63.1514(b)(6)(i) 

be changed to read, "Change label on the furnace to reflect uncontrolled operation." 

Response: The commenter correctly points out an inadvertent error in these two provisions. The 

final rule makes the appropriate corrections.

Comment #11: One commenter (0199) recommended that in paragraph §63.1514(c)(5)(iii), the 

text, “change the label on the furnace to reflect group 2 operation;” the label can be designed to 

reflect all planned operating modes and include compliant parameters for each mode.

Response: Because the operating mode of the furnace is not always obvious, the purpose of the 

label is to make clear to facility staff responsible for compliance, regulatory compliance 
27

inspectors, and others the current operating mode of the furnace. Therefore, it is necessary that 

the label affixed to the furnace communicate clearly the furnace’s current operating mode, rather 

than all potential or planned operating modes, so the recommended change is not appropriate. 

2.3 Hydrogen Fluoride Compliance

Comment #1: Commenters (0193, 0194) supported the EPA’s rationale for adding an HF limit 

for uncontrolled group 1 furnaces that is the same as the current HCl emission limit. The 

commenter observed that both chloride- and fluoride-based salt fluxes are used to remove 

impurities or to dry dross; chlorine and fluorine are chemically similar; and the amount of flux 

required largely depends on the amount of impurities to be removed. The commenter further 

stated that establishing a flux usage limit for chloride- and fluoride-based fluxes will limit HCL

and HF emissions from a furnace.

Response: The EPA acknowledges the commenters’ support.

Comment #2: One commenter (0199) recommended that in §63.151l(c)(9), because the EPA has 

already approved Method 26 for HCl in an alternative request, it should list Method 26 along 

with Method 26A.

Response: The EPA has listed Method 26 along with Method 26A.

2.4 Hydrogen Chloride Compliance

Comment #1: Commenters (0192, 0193, 0194) supported the addition of the HCl estimation 

technique provided in §63.1510(t)((2)(ii), but noted that the definition of reactive flux does not 

specify which fluxes are considered to be reactive, except to state that argon and nitrogen are not 

reactive. The commenters suggested that the EPA include sodium chloride and potassium 

chloride in the list of non-reactive fluxes. Commenters 0192, 0193 included two attachments that 

demonstrate that sodium chloride and potassium chloride do not produce HCl when used as flux 

in aluminum refining processes. The commenters expressed concern that not recognizing the 

scientific evidence that sodium chloride and potassium chloride are non-reactive and do not 

produce HCl would lead to an unrealistic estimate of chloride emissions and unnecessary

regulatory requirements with no environmental benefit. The commenters stated that this is 

particularly important for facilities that are area sources of HAPs and therefore do not have to 

test for HCl emissions. The commenters suggested that the rule language for §63.1510(t)((2)(ii) 

and §63.1512(e)(3) say, “chlorine contained in reactive flux” and “fluorine contained in reactive 

flux.”

Response: In addition to the commenters’ submissions, the EPA has obtained HCl emissions 

data from testing conducted at the Hydro Aluminum North America facility in Monett, Missouri. 

A test conducted on the Holding Furnace (EU0030) which receives molten metal from two 

melting furnaces and uses Metallpur®315 flux, which is primarily sodium chloride and 

potassium chloride, indicated low but detectable amounts of HCl (averaging 0.001 lb/ton for 3 

runs; test results are in the docket for this rulemaking). Based on the limited information 

available to the EPA including the commenters’ submissions and the Hydro Aluminum test 

results, the EPA concludes that use of flux containing sodium chloride and potassium chloride 

has the potential to produce HCl emissions. Therefore, we are not adding sodium chloride and 
28

potassium chloride to the list of non-reactive fluxes. We note that the Hydro Aluminum testing 

was conducted at a relatively low fluxing rate (25 pounds of flux per batch, 50 pounds of flux 

total per run of two batches) compared to furnaces such as rotary furnaces, which may use 

thousands of pounds of flux per furnace charge. For this reason, furnaces that use greater 

amounts of flux, if they use sodium chloride and potassium chloride fluxes, likely would have 

greater HCl emissions than the tested Hydro Aluminum furnace. However, we have revised the 

rule language for §63.1510(t)((2)(ii) and §63.1512(e)(3) to read, “chlorine contained in reactive 

flux” and “fluorine contained in reactive flux.”

Comment #2: One commenter (0196) requested that the EPA correct the definition of cover 

flux. The commenter indicated that the definition is unclear and inaccurate. The commenter 

stated that cover flux is not reactive, even if the molten metal bed is agitated or moved. The 

commenter stated that the definition of cover flux proposed in the new Secondary Aluminum 

MACT is technically incorrect and is inconsistent with the definition that the EPA has used to 

define flux in the secondary aluminum industry for 38 years. The commenter continued by

presenting the EPA standing definition of cover flux from the Air and Water Effluent Guideline 

for Aluminum Smelting (1974), given here:

Fluxing. The addition of a covering flux to the molten aluminum melt forms a 

barrier for gas absorption and oxidation of the metal. The flux also reacts with 

nonmetallics, residues from burned coating, and dirt in the scrap, collects such 

impurities and allows physical separation from the molten aluminum. The exact 

composition flux cover used varies from smelter to smelter, but is generally some 

combination containing one or more of the following: sodium chloride, potassium 

chloride, calcium chloride, calcium fluoride, aluminum fluoride, and cryolite. A 

common flux mixture is 47.5 percent NaCl, 47.5 percent KCl, and 5 percent 

cryolite. At the melting point of aluminum, the fluxes usually range from a tacky 

semisolid to a liquid depending on the composition of the mixture and the 

technique used to remove it from the melt.

The amount of flux used depends primarily on the material charged. Scrap 

containing a relatively large surface area, such as borings or turnings, creates 

large amounts of oxides and requires proportionally larger amounts of flux. The 

flux generally is added along with the aluminum scrap in amounts from less that 

10 percent to 33 percent by weight of the material charged.

The commenter (0196) discussed why cover flux is used and described the processes in great 

detail. The commenter also stated that cover flux (NaCl, KCl, and cryolite) is inert and harmless.

The commenter was concerned with the assertion that agitation of cover flux somehow causes 

reactions and increased emissions. The commenter indicated that calling cover flux reactive is 

inconsistent with the distinction between cover flux and reactive flux; and the physical 

constraints of processing secondary aluminum. The commenter recommended that the EPA 

should fix this inaccurate definition in the Final Rule, correcting terminology that defines cover 

flux as reactive flux if the metal bed is moved. 

Response: The commenter did not provide any stack test data that indicate that HCl is not 

formed when NaCl, and KCl are used as fluxes, or that HF is not formed when aluminum 
29

fluoride or cryolite is used in a flux. HF is known to be evolved from cryolite above 930F 

(500C) in the presence of water vapor (Alcoa MSDS for Synthetic Cryolite, available in docket 

EPA-HQ-OAR-2010-0544). However, we agree with the commenter that there are no test data 

indicating that agitation of the molten metal bath underneath a cover flux causes a cover flux to 

emit HAPs, and we have revised the definition of cover flux in the final rule as follows: Cover 

flux means salt added to the surface of molten aluminum in a group 1 or group 2 furnace, 

without surface agitation of the molten aluminum, for the purpose of preventing oxidation. Any

flux added to a rotary furnace is not a cover flux.

2.5 Operating Requirements/Work Practices

Comment #1: One commenter (0191) recommended that the agency not attempt to add 

specifications for cleaning processes such as those required for runaround scrap. The commenter 

did not believe that it is appropriate for the agency to delve into this topic and that the 

determination of the appropriateness of cleaning techniques be made in each affected facility.

The commenter continued that if it was the agency’s intention to continue to apply the 

requirements of the Subpart RRR rule to aluminum foundries that melt only clean charge and

operate a thermal chip dryer, then the EPA should have stated that such facilities are covered 

only for the requirements covering the thermal chip dryer. The commenter also suggested that 

the definition of clean charge should be restated in its entirety, and not simply as a subtext in the 

discussion of appropriate scrap cleaning techniques. One commenter (0197) noted that the EPA 

solicited comment on whether it is necessary to include specifications for cleaning processes, 

principally thermal drying and centrifuging, to ensure that materials qualify as clean charge. The 

commenter asserted that any specifications for cleaning processes are not necessary for 

aluminum chips because there are sufficient financial, operational, and safety incentives to 

ensure chips are “clean.” The commenter contended that such specifications are unnecessary for 

aluminum chips (“chips”) in thermal chip dryers, given that facilities have sufficient operational 

incentives to ensure that chips are clean before processing them in their units. The commenter 

further explained the processes and incentives for cleaning chips. The commenter also noted that 

setting specifications is impractical as cleaning processes vary with the type and amount of 

contamination.

Response: In the proposal, we solicited comments on what methods could be used for cleaning 

scrap to ensure that scrap processed by certain methods qualified as clean charge. We did not 

propose scrap cleaning requirements but were interested in gathering information on appropriate 

specifications that could be applied to cleaning processes that would produce clean charge. 

However, we did not receive any information and are not making any rule changes to address 

specifications for cleaning processes.

Comment #2: Commenters (0192, 0193, 0194, 0199) opposed the proposed change to the 

§63.1510(b) rule language related to the revision of OM&M Plans. The commenters noted that 

the current language in §63.1510(b) related to submittal of revised OM&M Plans does not 

contain a 60-day waiting period and was part of an EPA and Aluminum Association settlement 

agreement under litigation of the 2000 Secondary Aluminum NESHAP ( 67 FR 16374, April 5, 

2002). The commenters observed that the EPA provided no reason for changing this settlement 

agreement language, and thus did not provide the industry an opportunity to comment on the

EPA's new reasoning. The commenters stated that the current approach for OM&M Plan 
30

revisions works well for State agencies and operating facilities, so the revised rule language 

would simply result in an unnecessary 60-day delay in operations' ability to respond to product 

or market needs. The commenters requested that the proposed changes to §63.1510(b) be 

deleted, otherwise, the EPA should describe why the change is needed and provide an 

opportunity for the aluminum industry to comment on the EPA’s reasons. 

Commenter 0199 objected to the change because the OM&M Plan for a given facility commonly 

needs to be revised for any of a variety of reasons, such as the addition of a malfunction type, 

repair or replacement of equipment resulting in compliant operating parameter changes, new 

stack tests, or addition of new equipment, among others. The commenter observed that when 

these changes occur, it is necessary that the facility move forward and begin operating with the 

new procedures or parameters, without the need to wait for agency approval of the revised plan, 

or for a 60-day waiting period. The commenter noted that most states do not respond in any way

to the submittal of an OM&M Plan. The commenter stated that, under the existing procedure, if 

the permitting authority determines any revisions are necessary, the owner or operator assumed 

the risk by beginning to operate under the revised OM&M Plan upon submittal.

In a comment on the 2012 proposal and the 2014 supplemental proposal, commenter 0197 and 

0297 stated that regardless of the deadline set, the EPA should make clear that the source has 

achieved compliance by submittal of required documentation to the permitting authority in order 

to ensure that sources are not penalized for failure of regulatory authorities to act on submittals in 

a timely manner or situations where a regulatory authority requests plan revision and the preexisting OM&M plan remains in effect after the compliance period. The commenters stated that 

alternatively, the EPA could revert to the prior rule language, under which a facility would 

operate under a newly-submitted plan unless the Agency indicated that revision was needed, and 

then the facility would be given a reasonable time to accomplish revisions and operate in 

compliance with that revised plan after submission.

Response: In response to the comments, we have removed from the final rule the proposed 

provision that an owner or operator must not begin operating under a revised plan until approval 

is received or until after 60 days. 

Comment #3: Commenters (0192, 0193, 0194) stated that anodized aluminum is clean charge 

material. Commenter 0193 argued that the EPA did not provide any data or information on what, 

if any, HAPs are emitted from melting anodized scrap, and that most dyes are inorganic and are 

used at very low application rates therefore this should not alter the scrap material. Commenter 

0193 requested that the EPA maintain the current provisions.

Response: We proposed to clarify that anodized aluminum that contains dyes or sealants with 

organic compounds is not clean charge. Anodized aluminum containing organic dyes or sealants 

has the potential to result in formation of D/F when the aluminum is melted in secondary

aluminum production processes, in the same way that D/F can be formed when aluminum coated 

with paints, other coatings, or lubricants is melted. The commenters submitted no test data or 

other documentation to support their assertion that anodized aluminum containing dyes or 

sealants with organic compounds is different from aluminum with paints, coatings, or lubricants 

that are already excluded from the definition of clean charge, such that melting such anodized 
31

aluminum in a group 1 furnace does not result in emissions of D/F or other organic HAPs.

Therefore we are finalizing the provision as proposed.

Comment #4: The commenter (0197) indicated that the operation, maintenance, and monitoring 

provisions contained in section 63.1506(a)(5) of the proposed rule are redundant with the 

OM&M plan requirements and recommended that they should be deleted. The commenter stated 

that the OM&M plan requirements are sufficient to ensure compliance with the specific emission 

standards and work practices required under this Subpart. The commenter therefore proposed 

section 63.1506(a)(5) should not be included as a separate paragraph in this final rule.

Response: The OM&M plan requirements in section 63.1510(b) are consistent, and not 

redundant, with the provision in section 63.1506(a)(5) that an owner or operator must operate 

and maintain any affected source in a manner consistent with safety and good air pollution 

control practices for minimizing emissions. A determination of compliance with the provisions 

in section 63.1506(a)(5) include a review by the appropriate authority of information available 

including a review of operation and maintenance procedures, such as those contained in the 

OM&M plan. Section 63.1506(a)(5) is also consistent with the General Provisions in 40 CFR 63, 

Subpart A. We are adopting the revision to section 63.1506(a)(5) as proposed.

Comment #5: One commenter (0199) stated that the requirements of §63.1506(g)(5), (k)(3), and 

(m)(4) regarding continuous injection devices, may not be feasible in the case of repaired or 

replaced equipment, where a feeder setting may be lower on the repaired or replaced equipment 

than was established during the performance test while still providing the same lime flow rate 

(pounds/hour). According to the commenter, when this occurs, it should be sufficient to 

document the repair and show through a verification procedure that the lime flow rate is equal to 

or above the level established during the performance test at the new lime feeder setting.

The commenter suggested the following language be added:

“For a continuous injection device, maintain free-flowing lime in the hopper to 

the feed device at all times and maintain the lime feeder setting at or above the 

level established during the performance test. In the event the equipment is 

repaired or replaced after the performance testing has been conducted, and the 

feeder setting required to maintain the lime flow rate is lower than that established 

during the performance testing, that lower the lime feeder setting should be 

documented in the OM&M Plan.”

Response: In the final rule amendments, §63.1510(i)(4) has been revised as follows: “At least 

once per month, verify that the lime injection rate in pounds per hour (lb/hr) is no less than 90 

percent of the lime injection rate used to demonstrate compliance during your most recent 

performance test. If the monthly check of the lime injection rate is below the 90 percent, the 

owner or operator must repair or adjust the lime injection system to restore normal operation 

within 45 days. The owner or operator may request from the permitting authority for major 

sources, or the Administrator for area sources, an extension of up to an additional 45 days to 

demonstrate that the lime injection rate is no less than 90 percent of the lime injection rate used 

to demonstrate compliance during the most recent performance test. In the event that a lime 

feeder is repaired or replaced, the feeder must be calibrated, and the feed rate must be restored to 
32

the lb/hr feed rate operating limit established during the most recent performance test within 45 

days. The owner or operator may request from the permitting authority for major sources, or the 

Administrator for area sources, an extension of up to an additional 45 days to complete the repair 

or replacement and establishing a new setting. The repair or replacement, and the establishment 

of the new feeder setting(s) must be documented in accordance with the recordkeeping 

requirements of § 63.1517.”

In addition, §63.1517(b)(4)(ii) has been revised as follows:

“(ii) If lime feeder setting is monitored, records of daily inspections of feeder setting, including 

records of any deviation of the feeder setting from the setting used in the performance test, with a 

brief explanation of the cause of the deviation and the corrective action taken. If a lime feeder 

has been repaired or replaced, this action must be documented along with records of the new 

feeder calibration and the feed mechanism set points necessary to maintain the lb/hr feed rate 

operating limit. These records must be maintained on site and available upon request.”

Comment #6: One commenter (0199) noted that in regard to §63.1506(n)(l), “Maintain the total 

reactive chlorine flux injection rate and fluorine flux addition rate for each ...,” until additional 

tests are conducted we do not have a fluorine injection rate to monitor or maintain. 

The commenter recommended that terminology should be consistent. The commenter observed 

that the proposal is currently written as chlorine flux injection rate and fluorine flux addition rate. 

The commenter suggested that the terms should be either flux injection rate or flux addition rate 

for both chlorine and fluorine.

Response: The EPA agrees with the commenter and this paragraph has been revised in the final 

rule to say “...chlorine flux injection rate and fluorine injection rate....” However, the EPA 

thinks both terms are equivalent and are used interchangeably throughout the rule.

Comment #7: In a comment on the supplemental proposal, commenter 0299 supports the 

additions and changes as they apply to sweat furnaces and believes they provide greater clarity

and will improve understanding of the requirements for these facilities.

Response: The EPA acknowledges the commenter’s support of the rule requirements for sweat 

furnaces.

2.6 Other Technical Corrections/Clarifications

Comment #1: One commenter (0192) requested that the EPA allow facilities to terminate the 

required scrap sampling and analysis if the facility has strict purchasing specifications and has 

generated a long-term database that shows very low oil and coatings content in scrap purchased 

in accordance with the purchasing specifications.

Response: Owners or operators are responsible for inspecting scrap to confirm that the 

contaminant level is no greater than that of the scrap charged during the performance test.

Monitoring of scrap contamination is essential to demonstrate continuous compliance with the 

standard. Therefore, we are not changing the rule as recommended by the commenter.
33

Comment #2: One commenter (0192) agreed with the proposed change to the group 2 furnace 

definition to clarify that pots are not furnaces, but the commenter recommended that the words 

“to customers” should be deleted.

Response: In response to the comment, the last sentence of the definition of group 2 furnaces 

has been revised to read, “Unheated pots, to which no flux is added and that are used to transport 

metal, are not furnaces.”

Comment #3: Commenters (0193, 0194) asked that the EPA clarify the definition of an 

aluminum scrap shredder. The commenters expressed concern that the addition of the term 

"shearing" to this definition would redefine the affected source and expand the applicability of 

scrap shredder requirements well beyond the types of shredders that the EPA considered when 

developing the 2000 Secondary Aluminum NESHAP. The commenters noted that under the 

2000 NESHAP rule, the EPA established emission standards for aluminum scrap shredders that 

are stand-alone devices used to size a variety of aluminum scrap for further processing in a scrap 

dryer/delacquering kiln or furnace and have emission control devices to capture particulate 

emissions generated from crushing and grinding, as well as paints, coatings and other 

contaminants present on the scrap. The commenters’ concern is that the addition of the term 

"shearing" could expand applicability of the rule to continuous "shearing" operations used to cut 

aluminum plate, sheet or foil products to final width. The commenters explained that this type of 

shearing operation is not a stand-alone operation for processing scrap, does not generate 

significant particulate emissions and does not have separate capture or add-on air pollution 

control. The commenters concluded that NESHAP requirements for aluminum scrap shredders 

(e.g., 0.01 gr/dscf limit, bag leak detector, etc.) could therefore not be reasonably applied to this 

type of "shearing" operation.

The commenters recommended that the EPA either delete the proposed addition of the word 

"shearing" to the aluminum scrap shredder definition or clarify in the definition that "shearing 

and cutting operations performed at rolling mills and aluminum finishing operations (such as 

slitters) are not aluminum scrap shredders.”

Response: The definition has been revised by adding the sentence, “Shearing and cutting 

operations performed at rolling mills and aluminum finishing operations (such as slitters) are not 

aluminum scrap shredders.”

Comment #4: One commenter (0192) supported removing the outdated guidance document for 

bag leak detection systems. The commenter stated that the use of the manufacturers operating 

and maintenance instructions is the most reliable method for assuring proper operation of the 

systems.

Response: The EPA acknowledges the commenter’s support.

Comment #5: One commenter (0194) supported using manufacturer’s O&M instructions for bag 

leak detectors and deleting the reference to the EPA Triboflow leak detector guidance. The 

commenter stated that the leak detector guidance had caused confusion with respect to good 

practice for at least one of the commenter’s locations.

Response: The EPA acknowledges the commenter’s support. 
34

Comment #6: One commenter (0194) recommended that the added reference to “HF” in 

§63.1516(b)(2)(iii) should be deleted, because this provision relates to furnaces with add-on 

control devices and these furnaces are not subject to the new HF limit.

Response: We agree with the commenter and the final rule does not include the reference to 

HF in §63.1516(b)(2)(iii).

Comment #7: The commenter (0197) recommended that the EPA should clarify the definition 

of Clean Charge. The commenter noted that all materials listed in the first sentence are separated 

by semicolons with the exception of the final material, “runaround scrap”. The commenter stated 

that “runaround scrap” is a distinct and defined item and a semicolon should be inserted after the 

“or higher; and before the “and runaround scrap” to delineate it from the previous term.

In a comment on the supplemental proposal, Commenter 0286 stated that the EPA needs to 

clarify the definition of "clean charge" to be consistent with its guidance and policy found in the 

Agency’s Applicability Determination Index (ADI) Database. The commenter stated that on July

26, 2007, the EPA published in the FR recent postings to the ADI Database including 

determination M060039 (dated 03/01/2005), which provided guidance as to whether aluminum 

sows, ingots, and T-bars that have painted markings are considered clean charge under subpart 

RRR. According to the commenter, determination M060039 noted that there was a typographical 

error in the definition of clean charge and that the EPA intended these charge materials, 

"notwithstanding ink, grease or paint markings, should be treated as clean charge." The 

commenter stated that the EPA then published an amendment in the FR on October 3, 2005 

correcting a punctuation error found in the definition of clean charge and clarified that the phrase 

"known by the owner or operator to be entirely free of paints, coatings, and lubricants" should 

only apply to aluminum scrap. The commenter recommends that the EPA should take the 

opportunity to clarify that the phrase, "known by the owner or operator to be entirely free of 

paints, coatings, and lubricants" applies only to aluminum scrap and does not apply to charge 

materials such as T-bar, sow, ingot, billet, pig and alloying elements. The commenter 

recommend that, to ensure that the definition of “clean charge” is consistent with the EPA’s 

current policy and guidance on this matter as described in ADI M060039, the EPA add a 

sentence to the definition of clean charge (as proposed February 14, 2012) to read as follows: 

"Clean charge means furnace charge materials, including molten aluminum; T-bar; sow; 

ingot; billet; pig; alloying elements; aluminum scrap known by the owner or operator to 

be entirely free of paints, coatings, and lubricants; uncoated/unpainted aluminum chips 

that have been thermally dried or treated by a centrifugal cleaner; aluminum scrap dried 

at 343 °C (650 °F) or higher; aluminum scrap delacquered/decoated at 482 °C (900 °F) or 

higher, and runaround scrap. Aluminum T-bars, sows, ingots, billets, pigs and alloying 

elements notwithstanding ink, grease or paint markings, are clean charge. Anodized 

aluminum that contains dyes or sealants with organic compounds is not clean charge."

Response: The comma following “or higher” has been replaced with a semi-colon in the final 

rule amendments to promote ease of reading; however, this is not a substantive change.

Regarding the comment received on the supplemental proposal concerning the definition of 

“clean charge” and certain aluminum sows, ingots, and T-bars, the scope of the 2014 
35

supplemental proposal was limited to discrete topics that we expressly stated did not include 

“clean charge definition.” 79 FR at 72884. Even in the 2012 proposal, our proposed revision to 

the definition of “clean charge” only addressed the topic of anodized aluminum. Accordingly, 

this comment is outside the scope of this rulemaking, and no action was taken in the final rule in 

response to the commenter's request.

Comment #8: One commenter (0199) suggested that in §63.1503 the definition of “tap” be 

revised to read: “Tap means the portion of an operating cycle when processed molten aluminum 

is poured from a furnace.” The commenter expressed concern that as proposed, there may be a 

problem when conducting stack testing of multiple furnaces. The commenter noted that the 

commenter currently conducts stack testing of multiple furnaces with each one starting at a 

different point in the operating cycle and continuing through a complete operating cycle for each 

furnace, with each cycle containing a number of operating tasks including charging, melting, 

skimming, alloying, and tapping. The commenter stated that these stack tests have been accepted 

by both the EPA and the states. The commenter explained that for stack testing purposes, the 

beginning or end of the cycle can be at any point as long as all tasks are accomplished, meaning 

that tapping should not be defined as the end of the furnace cycle, rather tapping should only

refer to the removal of molten aluminum from the furnace. The commenter noted that the 

commenter would not have the personnel required to simultaneously test multiple furnaces if the 

test runs all had to begin concurrently with charging and end with tapping.

Response: To address the commenter’s concern, we have revised the definition of “tap” as 

follows, to address the commenter’s concern: “Tap means the end of an operating cycle of any

individual furnace when processed molten aluminum is poured from that furnace.”

Comment #9: One commenter (0199) stated that the EPA has recognized through test plans and 

alternative requests that a facility can use both charge pounds and aluminum produced pounds 

within the same facility for different furnaces. The commenter provided as an example the 

commenter’s Aleris Rolled Products, Inc. facility in Lewisport, Kentucky, which has melting 

furnaces that use pounds charged while the holders use calculated aluminum pounds produced. 

The commenter noted that this particular case is documented in the "Lewisport Uncontrolled 

Reverberatory Furnace Test Protocol", Appendix G in the commenter’s Consent Decree 

(attached to comment letter). The commenter maintained that there is no justification for 

restricting individual furnaces from using pounds of aluminum produced or pounds charged 

when determining compliance.

Response: The proposed rules did not include changes to subpart RRR requirements regarding 

whether individual furnaces should be allowed to use pounds of aluminum produced or pounds 

charged when determining compliance and we do not believe a rule change is necessary based on 

the information available to the EPA.

Comment #10: One commenter (0193) supported the proposed addition of the new edition of 

the ACGIH guidelines manual for hooding requirements and allowing the older reference to 

remain. However, the commenter stated that due to the many different furnace types and 

configurations, the rule should be modified, with similar wording as is in the current Iron and 

Steel Foundry Area Source MACT, to state that each capture and collection system must be 

designed using acceptable engineering standards, such as those published by the American 
36

Conference of Governmental Industrial Hygienists. According to the commenter, this would 

allow hoods to be designed using the ACGIH guidelines as they were intended, as guidelines to 

assist in the design of capture and collection systems. The commenter recommended that the 

EPA clarify in the rule that the ACGIH-manual hooding specifications are intended to be used as 

guidelines, and that good engineering practices be included for site-specific instances where 

ACGIH hooding specifications are not practical and/or other engineering designs can be 

effective.

The commenter argued that the hooding guidelines promulgated by ACGIH were not intended to 

be regulation. The commenter stated that certain limitations exist within the guideline language 

that should be addressed by the EPA with engineering alternatives on a site specific basis. 

According to the commenter, where ACGIH hooding specifications are not practical due to 

furnace design, safety, and operating limitations/access, the EPA should consider work practice 

standards for furnace operations to minimize the potential for fugitive emission releases.

Commenter 0197 contended that the 23rd and 27th edition of Industrial Ventilation: A Manual of 

Recommended Practice, American Conference of Governmental Industrial Hygienists (“ACGIH 

Manuals”), do not contain specific requirements to guide facilities and should not be 

incorporated wholesale, by reference, into regulations. The commenter stated that EPA, in 

promulgating emission standards must explicitly state the requirements. The commenter 

recommended that the EPA should remove the reference to the ACGIH manuals, as well as the 

requirement in proposed section 63.1502 that capture and collection systems meet ACGIH 

Standards, the EPA should specify the elements that it believes are important and required so that 

the regulatory requirements are clear, and to the extent the manuals are referenced in the final 

rule, the EPA must specify which particular aspects of the manuals are being incorporated.

In a comment on the supplemental proposal, commenter 0297 stated that in the supplemental 

proposal, the EPA plans to provide an alternative to the ACGIH Manuals for design, installation, 

and operation of sweat furnaces only, and would not allow alternatives to the ACGIH Manuals 

for capture and collection systems installed on other sources subject to the rule. As they stated in 

their comments on the 2012 proposal, incorporating the ACGIH Manuals and requiring systems 

to be designed and installed to meet the ACGIH standards is inappropriate; the EPA must 

explicitly state the requirements as the ACGIH Manuals do not provide specific requirements for 

a facility to follow. The commenter stated that the 2012 proposal appears to actually exacerbate 

the problem in that it incorporates the entire manual rather than just sections 3 and 5. The 

commenter stated that due process and basic principles of rulemaking under the Administrative 

Procedure Act and Clean Air Act require the EPA to reasonably inform regulated entities of their 

obligations, but because the ACGIH Manuals are voluminous and it is unclear which specific 

aspects of the manual the EPA is intending to incorporate, finalizing the rule as proposed would 

contravene these fundamental legal requirements. The commenter stated that the manuals 

provide the general ventilation equations and simple diagrams for hoods and ductwork, also 

providing a framework to design simple conveyance systems; it does not and was not intended to 

address complex industrial exhaust systems with wide ranges of temperatures. The commenter 

stated that, thus, it is unclear what specific requirements from the manual the EPA intends to 

incorporate in proposed section 63.1506(c)(1) for the complex operations regulated here; under 

this proposal, sources will not have fair notice of the operating requirements for capture and 

collection systems.
37

Commenters (0192, 0193, 0199) requested that Secondary Aluminum Production facilities be 

allowed to use any ACGIH manual edition from the 23rd on rather than restricting the industry to 

the 23rd and 27th editions. 

Commenter 0192 supported the EPA’s decision to allow use of the updated 27th edition of the 

ACIGH manual, and recommended that the EPA allow the use of any future editions that may be 

published. The commenter noted that the 27th edition has been renamed: “Industrial Ventilation: 

A Manual of Recommended Practice for Design.” 

Response: We acknowledge commenter 0193’s support for allowing the use of either the 23rd or 

27th edition of the ACGIH Guidelines manual. In the preamble to the proposed rule, we solicited 

comment on whether there are alternatives to the ACGIH guidelines, such as ventilation rules or 

guidelines developed by other professional organizations, governmental agencies, or industry

organizations that could be used in a more flexible rule provision. We also solicited comment on 

other ways to increase flexibility, such as using minimum face velocity, elimination of visible 

emissions, minimum pressure drop, or other suitable parameters to determine capture 

effectiveness. We did not receive any information from commenters or others on the potential 

parameters we listed but received the comments summarized above. We note that commenter 

0193 requests that the rule provision be broadened to allow “acceptable engineering standards, 

such as those published by the [ACGIH]” and argues that the ACGIH manual be treated as 

guidelines as opposed to regulatory requirements, while commenter 0197 takes a different

approach, asserting that the EPA should explicitly state the particular elements in the ACGIH 

manual that are required by the rule or preferably remove the regulatory reference to the ACGIH 

manual entirely. Based on our experience implementing the rule and in light of the lack of any 

comments containing recommended alternative ventilation rules or guidelines, as well as the lack 

of comments on potential capture efficiency parameter approaches listed by the EPA at proposal, 

we conclude there is no reason to adopt an approach different from the current one, i.e., 

incorporating by reference the ACGIH manual, with the revisions adopted in the final rule to 

allow use of the 27th edition in addition to the 23rd edition. We do not consider “acceptable 

engineering standards” to be sufficient or appropriate for capture and collection systems in this 

rulemaking, because this language does not provide sufficient guidance to the secondary

aluminum industry and to permitting authorities as to what constitutes adequate capture and 

collection systems under the relevant provisions of subpart RRR. We also believe it is not 

necessary to revise the rule to specify particular elements of the ACGIH manual. We note that 

site-specific issues may continue to be addressed as facilities work with the EPA and delegated 

authorities during implementation of the rule. Accordingly, we are retaining the incorporation by 

reference of Chapters 3 and 5 of the 23rd edition and adding all of the 27th edition of the ACGIH 

Industrial Ventilation manual, as proposed.

The final rule incorporates by reference Chapters 3 and 5 of the 23rd edition, and the entire 27th

edition, and the final rule accounts for the correct title of the 27th edition (“Industrial Ventilation: 

A Manual of Recommended Practice for Design”). However, it is not appropriate to incorporate 

by reference future editions of a document; in general, only editions already published may be 

incorporated by reference. 

In further response to the comment on the 2014 supplemental proposal concerning a proposed 

alternative to ACGIH Guidelines being limited to “sweat furnaces only”, the commenter does not 
38

appear to oppose the proposed alternative for sweat furnaces but instead reiterates and 

supplements its comments on the 2012 proposal that ACGIH Guidelines should not be 

incorporated into Subpart RRR requirements. We have responded to the commenter’s 2012 

comments above, and to the extent the commenter provided new or additional comments in 

response to the 2014 supplemental proposal, they are outside the scope of that notice, which was 

limited to discrete topics that we expressly stated did not include “ACGIH Guidelines.” 79 FR at 

72884.

3. Testing and Monitoring

Comment #1: One commenter (0192) objected to the proposed language that “Performance tests 

be conducted under such conditions as the Administrator specifies based on representative 

performance of the affected source for the period being tested” under §1511(a). The commenter 

noted that this language seems to be extracted from subpart A section 63.7(e) but is incomplete 

and in a different context. The commenter questioned whether it has a different meaning in 

proposed subpart RRR. The commenter stated that if it does have a different meaning, it has not 

been explained or justified in the proposal; if it does not have a different meaning, it is 

unnecessary, and because it is incomplete and out of context, could lead to confusion. The 

commenter recommended that it should be deleted in either case.

Response: As discussed in the proposed and final rule documents, subsequent to a court decision 

we are eliminating the SSM exemption in subpart RRR, requiring that standards apply at all 

times, and making revisions to the applicability of the General Provisions. As in the proposed 

rule, the final rule removes from subpart RRR, Appendix A the applicability of §63.7(e)(1), 

which contains superseded references to periods of SSM, and revises §63.1511(a) to reflect 

pertinent portions of §63.7(e)(1). The commenter did not explain why it says revised §63.1511(a) 

is incomplete, out of context, and confusing, but making §63.7(e)(1) not applicable eliminates 

any conflict between the two provisions.

Comment #2: Commenters (0193, 0194) stated that monthly verification of lime injection rate is 

unnecessary and overly burdensome given that lime feed measurement is not likely to change 

significantly over short periods of time. The commenter recommended that the EPA establish a 

lime rate verification frequency of “at least once every 6 months” which would be consistent 

with all other monitoring devices used under the Secondary Aluminum NESHAP.

Commenter 0192 suggested that the EPA should exempt facilities with automated systems based 

on load cells to assure adsorbent flow from this requirement, as these systems create alarms or 

error messages when adsorbent flow is interrupted, making periodic verifications not necessary.

One commenter (0199) objected to the requirements of §63.1510(i)(4): “At least once per month, 

verify that the lime injection rate in pounds/hour (lb/hr) is no less than 90 percent of the lime 

injection rate used to demonstrate compliance during your performance test.” The commenter 

asserted that this proposed measure contravenes the standard negotiated in a 2009 Consent 

Decree resolving a federal enforcement action against the company. The commenter agreed that 

lime flow rate is the important parameter and that it is necessary to periodically verify lime flow 

rates, but asserted that it is not necessary to verify lime flow rates monthly.
39

The commenter explained that under their Consent Decree, two time periods are used for the two 

lime flow rate methods: measuring volumetrically or using a scale. The commenter stated that if 

a scale is used, the Consent Decree provides that the commenter checks scale calibration semiannually, and if the lime flow rate is determined volumetrically, it is appropriate to perform a 

routine verification. The commenter explained that where this has been necessary, the Consent 

Decree provides for bi-monthly verification if flow is monitored visually as required by 

§63.1510(i)(1)(i), and verification once every four (4) months if flow is monitored electronically

as in §63.1510(i)(1)(ii). 

Response: The lime injection rate is a necessary parameter established during performance test 

to ensure continuous compliance with the emission standard, in the absence of monitoring 

emissions on a continuous basis and in light of performance testing that is required only every 5 

years. Operation with potentially inadequate lime injection for a period of up to six months 

before the need for corrective action is determined could reduce the effectiveness of or damage 

the control device and thereby increase emissions above the emission standard. The commenters 

did not submit any supporting documentation for their assertions that monthly verification is 

“overly burdensome” or that lime feed measurement is “not likely to change significantly over 

short periods of time.” Facilities with automated systems based on periodically calibrated scales 

or load cells should be able to verify lime injection rate easily by integrating the recorded hopper 

weight loss. Therefore, we are adopting the requirement as proposed.

Regarding the 2009 Consent Decree, the decree at paragraph 122 states clearly that each 

company is responsible for achieving and maintaining complete compliance with all applicable 

federal laws and regulations, and compliance with the Consent Decree does not necessarily mean 

compliance with the Clean Air Act or implementing regulations. Further, the Consent Decree 

does not limit the EPA’s authority to revise subpart RRR.

Comment #3: Commenters (0192, 0193, 0194) stated that the new list provided in §1510(a) 

adds the phrase "including, but not limited to,” which does not clarify which provisions of 

Subpart RRR actually apply to area sources. The commenters requested that the EPA delete the 

phrase from §1510(a). The commenter observed that if something is missing from §1510(a)(1) 

through (19), it should be added to provide clarity for area sources.

Response: Owners or operators of area sources are subject to monitoring requirements for those 

affected sources listed in §63.1500(c)(1)-(4). We are not changing the language in 63.1510(a) 

because the list is intended to be informational and a guide to applicable requirements to assist 

compliance by area sources, not to alter the applicability of promulgated Subpart RRR 

requirements. In addition to the requirements listed in § 63.1510(a), they must conduct whatever 

monitoring is necessary to ensure that these affected sources are operated in a manner consistent 

with safety and good air pollution control practices.

Comment #4: Commenters (0192, 0193) requested that the requirement, “for the purpose of 

annual certifications of compliance required by 40 CFR part 70 or 71, the owner or operator of a 

major or area source subject to this subpart must certify continuing compliance” be removed, as 
40

this would result in an additional requirement for area sources and it is a Title V reporting burden 

that was specifically exempted for the secondary aluminum production.5

Response: After review of the comments received, we agree this requirement would impose 

additional burden on area sources subject to Subpart RRR and provide limited benefit. We note 

the existing rule generally exempted secondary aluminum area sources from Title V permitting, 

and we did not propose to remove the exemption. The proposed compliance certification 

requirement for area sources is not included in the final rule.

Comment #5: Commenters (0193, 0194) stated that the proposed §63.1511(g)(5) states that "[i]f 

the owner or operator wants to conduct a new performance test and establish different operating 

parameter values, they must meet the requirements in paragraphs (g)(1) through (4) of this 

section and submit a revised site specific test plan and receive approval in accordance with 

paragraph (a) of this section." The commenters observed that paragraphs (g)(1) through (4) of 

this section are only relevant if an owner or operator wants to "use existing data in addition to the 

results of performance tests to establish operating parameter values....”, but are not relevant if the 

facility "wants to conduct a new performance test and establish different operating parameter 

values.” The commenters suggested that the new §63.1511(g)(5) should be revised to delete the 

reference to paragraphs (g)(1) through (4) to say: "[i]f the owner or operator wants to conduct a 

new performance test and establish different operating parameter values, they must submit a 

revised site specific test plan and receive approval in accordance with paragraph (a) of this 

section."

Response: The requirements of §63.1511(g)(1) through (4) apply to cases where an owner or 

operator wants to conduct a new performance test and establish operating parameter values, and 

in doing so wants to use existing data in addition to the results of the new performance test to 

establish operating parameter values for compliance monitoring. In the final amendments, 

paragraph (g) (5) has been revised to read, “If the owner or operator wants to conduct a new 

performance test and establish different operating parameter values, they must submit a revised 

site specific test plan and receive approval in accordance with paragraph (a) of this section. In 

addition, if an owner or operator wants to use existing data in addition to the results of the new 

performance test to establish operating parameter values, they must meet the requirements in 

paragraphs (g)(1) through (4) of this section.”

Comment #6: Commenters (0192, 0194) supported the EPA’s clarification that multiple new 

SAPUs are allowed under the rule. Commenter 0194 stated that creating a separate new SAPU 

greatly simplifies compliance and emissions sampling where multiple affected sources are 

controlled by a single lime-injected baghouse. Commenter 0192 agreed that grouping furnaces 

logically, based on their use, can make compliance calculations more straightforward. The 

commenter proposed that this concept should be extended to existing source SAPUs. 

Response: The EPA acknowledges the commenters’ support for the revision providing for 

multiple new SAPUs, but we did not propose and are not finalizing a revision to allow multiple 

existing SAPUs, because it is only necessary to have one existing SAPU. 

 

5 March 25, 2005 proposal and the December 19, 2005 final rule. EPA performed a thorough evaluation and

concluded that the additional reporting was an “unnecessary burden” and would not improve compliance.
41

Comment #7: In a comment on the supplemental proposal, commenter 0295 stated that they 

have concerns with the requirements found is sections 63.1510(d)(2)(ii)(D) and 

63.1510(d)(2)(iii)(B) regarding the maintenance of readings ‘at or above 90 percent’ of the 

pressure differential or fan RPMs in order to utilize the listed alternatives to annual flow rate 

measurements. The commenter stated that the 90 percent criteria are too restrictive to be of any

practical benefit in the rule. This level of consistency is not routinely demonstrable for pressure 

differential and fan RPMs, especially for those involving an emission control device. The 

inherent repeatability of the measurement method itself already introduces variability of plus or 

minus ten percent when accounting for the repeatability of the test methods and equipment. In 

addition, hood static pressure can vary depending on the amount of dust loading on a fabric filter 

and the stage of cleaning associated with that filter, even when systems are operating normally. 

To account for this measurement and inherent system variability, the commenter believes that the 

regulatory requirement should be 80 percent of the indicator values.

In a comment on the supplemental proposal, commenter 0286 stated that, regarding the proposed 

alternatives (ventilation duct differential pressure or the fan revolutions per minute) to the use of 

Methods 1 and 2 for annual monitoring of capture/collection and closed vent systems 

(63.1510(d)(2)), the proposed requirement to maintain the measured parameter at or above 90 

percent of the value measured during the most recent Method 2 test, is too restrictive to be of any 

practical benefit. The commenter stated that, presumably, if the alternative parameter is below 90 

percent of the indicator value for any day of the year, the facility would be required to revert to 

measuring the air flow rate during that year to demonstrate compliance with the rule. The 

commenter stated that while this level of consistency may be representative for other types of 

parameters (e.g., oxygen content consistency in flue gases), it is not routinely demonstrable for 

pressure differential and fan RPMs, especially those involving an emission control device. The 

commenter stated that the inherent repeatability of the measurement method itself introduces 

variability of plus or minus 10 percent when accounting for the repeatability of the test methods 

and equipment; in addition, hood static pressure can vary depending on the amount of dust 

loading on a fabric filter and the stage of cleaning associated with that filter, even when systems 

are operating normally. The commenter stated that the allowable variability should be on the 

order of 80 percent of the indicator values to account for this measurement and inherent system 

variability.

Response: Where the EPA establishes a parametric operating limit to provide assurance of 

compliance associated with the performance of an operating parameter during a performance 

test, we rely on the capability of the facility to operate their equipment and emissions control 

devices, including those associated with parametric monitors, at the same level of operation as 

observed during the performance test. The parametric monitor must be a device capable of 

providing compliance assurance between emissions test events and capable of demonstrating 

when a distinct change in operation of the source or emissions controls has occurred. In the 2014 

proposal, we proposed the daily monitoring of fan rpm as an alternative to the annual flow rate 

measurements. As a result of comments and the EPA’s consideration of the comments, this rule 

provides alternatives to the requirement to conduct annual flow rate measurements of 

capture/collection and closed vent systems; all but one requires a parameter to be recorded daily

and maintained at no less than 90 percent of the average value recorded during the most recent 

Method 1 and 2 performance test. Alternative monitoring parameters include differential 

pressure; fan RPM or fan motor amperage; static pressure measurements; duct centerline velocity 
42

using a hotwire anemometer, ultrasonic flow meter, cross-duct pressure differential sensor, 

venturi pressure differential monitoring or orifice plate equipped with an associated 

thermocouple. These monitoring alternatives rely on information from the parametric gauge 

reading as an indicator that a compliant volumetric flow rate is being achieved during the period 

between performance tests, which under these alternatives is extended to every five years.

Variability in emissions test results is widely held to be +/- 15 percent6, whereas parametric 

monitoring devices such as thermocouples can be calibrated to +/- 2 percent, pressure sensing 

devices to +/- 1%, amp meters to +/- 2 percent accuracy. Facilities should choose 

instrumentation that is capable of providing repeatable and accurate readings for their parametric 

monitoring records. Annual calibration of such devices is recommended, but not required by the 

rule. Furthermore, parametric monitors track trends that are generally not associated with process 

or other operational fluctuations, for instance an increase in production rate does not have a 1:1 

relationship with an increase or decrease in fan motor amperage. So with parametric monitoring 

requirements, 90 percent (also described as a 10 percent deviation from the emissions test 

average) of the emissions test parametric reading average is selected as the trigger point for 

corrective action because it describes a control decision point; one where the monitoring data 

show that a process or control change has occurred. Where facilities are concerned that their 

parametric monitors may not provide this level monitoring assurance they would be well served 

to research the precision of the devices they currently have installed or plan to install and 

consider having their device(s) calibrated or choose one of the other compliance alternatives 

such as an annual direct flow rate measurement that does not rely on daily parametric monitoring 

measurement. With these devices calibrated or otherwise functioning normally the EPA believes 

that monitoring and maintaining a 90 percent operating requirement such as those in the

monitoring alternatives provided in the rule is achievable for all facilities that are tracking their 

process rates regularly. In addition, neither commenter provided any data to support their 

arguments that a 90 percent level is inappropriate or that 80 percent is more appropriate.

Comment #8: In a comment on the supplemental proposal, commenter 0286 stated that the 

provisions for permanent total enclosures (63.1510(d)(2)(iv) acknowledges the potentially wide 

array of explanations for a measured parameter being outside an identified range by including a 

provision to investigate and restore systems when such a parameter is measured on occasion. The 

commenter stated that given the variability associated with ventilation systems and the 

requirement for daily parameter readings, a similar provision should be included for dealing with 

occasional static pressure and RPM measurements that are outside the applicable indicator value 

range and recommends that an provision such as follows be added to section 63.1510 (d)(2)(ii) 

and (iii):

"When there are daily readings below 90 percent of the differential pressure 

(alternatively, RPM) measured during the most recent Method 2 performance test series, 

the facility may investigate and take steps to restore normal operation, in lieu of 

performing an annual flow rate measurement, provided that the reasons for the low 

reading are recorded."

 

6

(ReMAP): PHASE 1, Precision of Manual Stack Emission Measurements; American Society of Mechanical 

Engineers, Research Committee on Industrial and Municipal Waste, February 2001.
43

Response: The EPA disagrees with the suggested revisions provided by the commenter. For 

parametric monitoring that is used by the source, instead of annual flow rate measurements, to 

assure continuous compliance with emission standards in the rule, corrective action must be 

taken to maintain monitoring parameters at or better than their performance testing baseline. 

Where a parameter deviates more than ten percent from this mark as an average value the EPA 

recognizes that the operation of the control responsible for the parameter being monitored has 

changed significantly and that the owner or operator must make the necessary repairs or 

adjustments to restore normal operations.

Comment #9: In a comment on the supplemental proposal, commenter 0294 stated that the 

EPA's proposal to incorporate permanent total enclosures (PTE) and the alternative inspection 

requirements for PTE are practical in the context of the affected sources within the secondary

aluminum source category.

Response: The EPA acknowledges the commenter’s support of the proposed rule language and 

the use of PTE in this respect.

Comment #10: The commenter (0197) stated that the EPA included thermal chip dryers in the 

lime injection monitoring requirements. The commenter believed that the inclusion of thermal 

chip dryers in proposed section 63.1510(a)(8) appears to be inadvertent because lime-injected 

fabric filters are not used as a control device for thermal chip dryers. If the addition of this 

requirement was not inadvertent, the commenter noted that it is inappropriate because the EPA 

did not provide notice, nor did it provide an explanation of why thermal chip dryer emissions 

should be controlled by a lime-injected fabric filter. The commenter recommended that thermal 

chip dryers should be removed from section 63.1510(a)(8).

Response: Lime injected fabric filters are not required for control of emissions from thermal 

chip dryers under the existing rule or the final amendments. However, if a lime injected fabric 

filter is used at the discretion of the owner or operator during the performance test, then it must 

continue to be used and the lime injection rate established during the performance test must be 

maintained.

3.1 Testing Uncontrolled Group 1 Furnaces

Comment #1: In a comment on the supplemental proposal, commenter 0290 stated that as a part 

of the procedures to minimize untested fugitive emissions, the EPA should allow facilities to 

develop testing procedures on a case-by-case basis to demonstrate that the 67 percent capture 

efficiency assumption is not appropriate. The commenter stated that such a testing procedure 

might apply in particular to D/F emissions that are produced as a result of organic substances 

introduced with purchased scrap. According to the commenter, in a batch process those organic 

substances and their decomposition products have been emitted by the time the furnace charge 

has achieved a molten state and in some processes, the furnace remains completely closed up 

during the melting phase of the process and essentially 100 percent of emissions go up the stack. 

The commenter stated that a sequence of simultaneous stack tests with different durations could 

demonstrate that all D/F evolution occurs before the furnace is opened to perform necessary

refining operations.
44

Response: It is possible that significant D/F evolution may occur when other-than-clean charge 

is initially placed in the furnace, while the furnace doors are open. If this is indeed the case, D/F 

capture might actually be lower than for pollutants like HCl. This possibility is supported by 

testing conducted at Southwire on September 5, 2007 (see table). In that testing, only 42 percent 

of the total D/F measured was in the furnace stack; this value was actually lower than the 

average of 71 percent for all pollutants and all tests (and on which the proposed 67 percent 

capture assumption was based). If D/F is emitted when the furnace doors are open, and escapes 

through open furnace doors, there would not necessarily be a relationship between the D/F 

capture efficiency and the amount of D/F generated during various times in the cycle. Therefore, 

it is not appropriate to measure the D/F emitted at various times during the cycle and attempt to 

estimate a capture efficiency based on those data. Therefore, the EPA believes that it is not 

appropriate to measure D/F in a sequence of simultaneous stack tests with different durations to 

infer a particular D/F capture efficiency, and such testing procedures are not allowed in the final 

rule.

Southwire Test Results Summary

Test Report Date Pollutant

Three-run Average

Fraction in Furnace Stack

Three-run Average

Fraction in Canopy Hood 

Stack

June 26, 2007 PM 0.78 0.22

June 26, 2007 HCl 0.81 0.19

June 26, 2007 D/F 0.97 0.03

Sept. 5, 2007 PM 0.49 0.51

Sept. 5, 2007 HCl 0.77 0.23

Sept. 5, 2007 D/F 0.42 0.58

Average for all All 0.71 0.29

However, it would be possible to estimate capture efficiency on a case-by-case basis by, for 

example, using the building as an enclosure, and measuring D/F emissions from powered roof 

vents. Such case-by-case demonstrations would need to be approved by the appropriate

authority. Additionally, in light of comments, we have re-examined the Southwire testing data on 

which the proposed 67-percent capture efficiency assumption was based, and have revised the 

assumed capture efficiency to 80 percent.

3.2 Worst Case Scenario Testing

Comment #1: In a comment on the 2012 proposal, one commenter (0199) asked that the EPA 

address and clarify in §63.1511 that stack testing is to be conducted when charging the worstcase material likely to be processed in the affected source. The commenter explained that this 

may mean multiple tests of separate charge material consisting of dross and separate charge 

material with high oil or other organic material, and for some sources, this will mean testing of a 

worst-case blend of these materials. The commenter suggested that the EPA provide clarification 

that the desired results from these tests are in fact "worst -case emissions expected under normal 

operations," and that this is not representative performance, as the new language implies.
45

The commenter also recommended that the EPA clarify that these worst case charge materials, 

and blends of these, have differing process rates and, therefore, the charge rate from the stack 

tests is not representative of the production rate that will be achieved during normal operations.

The commenter requested that until the EPA addresses these additional critical issues, the EPA 

acknowledge and confirm that the agreed-upon stack testing protocols from the Consent Decree 

are not impacted by this rule making and remain fully acceptable.

In comments on the 2012 proposal, commenters (0192, 0193, 0194) stated that in regard to 

changes proposed for the performance test language in paragraph §63.1511(b)(1), requirements 

to conduct a performance test at "the highest production rate" and "with the scrap containing the 

highest level of contamination" are mutually exclusive and such a requirement would not be 

workable. The commenters noted that the highest furnace production rates or throughputs are 

obtained when processing large uniform pieces of aluminum. The commenters observed that 

scrap with this sort of geometry (small surface area to weight ratio) contains less "contaminants" 

such as oil, paint or other materials per furnace charge than a scrap consisting of many small 

pieces, while production rates or throughput are lower when processing smaller, non-uniform 

scrap because of a lower density which takes up more space in the furnace. 

Commenter 0197 recommended that performance tests for thermal chip dryers should be 

conducted under representative operating conditions. The commenter recommended that the 

EPA should clarify this point in the final rule by revising Proposed section 63.1511(b)(1) to state 

that chips should contain representative levels of contamination expected to be seen under 

typical unit operating conditions.

Commenters 0193, 0194 expressed concern that the EPA's revision to §63.1511(b)(1) could lead 

to the need for two or more performance tests on each furnace to cover multiple rates of 

production, even though worst case emissions can clearly be represented by a single test 

condition under the current regulatory requirement in §63.1511(b)(1), and could double 

compliance testing costs for companies without good cause. The commenters requested that 

either the EPA delete the change to section §63.1511(b)(1) or describe why this is change is 

necessary and provide an opportunity for the aluminum industry to comment on the EPA's 

rationale.

In a comment on the supplemental proposal, commenter 0295 stated that while they concur with 

the changes that the EPA has made in the testing condition requirements as found in section 

63.1511(b)(1) versus what was included in the 2012 proposal, it appears that the parenthetical 

inclusion of the word “normal” in the first sentence is un-necessary and potentially confusing. 

The commenter stated that it is not clear what “normal’ means in the context of testing 

conditions expected to produce the highest level of HAP emissions. According to the 

commenter, historically, facilities have been known to establish an upper limit of what emissions 

might be by testing under conditions that are outside “normal” operations; for example, a facility 

that normally melts 30 to 40 percent purchased scrap in a group 1 uncontrolled furnace might test 

at 100 percent purchased scrap to set an upper bound of potential emissions. The commenter 

stated that a facility might accumulate purchased scrap of lower than average acceptable quality

in order to make up a test with dirtier than usual charge materials. The commenter stated that test 

results from these activities are legitimate if the emission limits are met, even though the charge 
46

is outside the “normal” range. The commenter recommended that the EPA remove the 

parenthetical “normal” from the text in section 63.1511(b)(1).

In a comment on the supplemental proposal regarding the EPA’s modification to section 63.1512 

to include a requirement for performance tests to be conducted “under representative (normal) 

conditions,” commenter 0290 stated that it is not clear what this means in the context of worstcase testing. The commenter stated that in the past, facilities have established an upper limit of 

what emissions might be by testing under conditions that are outside routine operations. The 

commenter stated that test results are valid if the emission limit is met, even though the charge is 

outside the “normal” range; facilities have routinely used these and other means to achieve 

“worst case” conditions for a test. The commenter recommended that the EPA should remove the 

parenthetical “(normal)” and clarify that testing outside of the routine range of operations is 

allowed as long as it is representative of worst case.

Response: In the 2012 proposal, we proposed amendments to clarify that performance tests 

under multiple scenarios may be required in order to reflect the emissions ranges for each 

pollutant regulated under Subpart RRR. We received comments on the 2012 proposal that the 

worst case charge materials, and blends of these, have differing process rates and, therefore, the 

charge rate from the stack tests is not representative of the charge rate that will be achieved 

during normal operations. Based on the comments received on the 2012 proposal and 

recognizing that it may be necessary to conduct performance tests under one or multiple 

scenarios to be representative of the range of normal operating conditions, in the 2014 

supplemental proposal we proposed revised language in 40 CFR 63.1511(b)(1) to clarify the 

conditions under which subpart RRR performance tests must be conducted. The intention in the 

subpart RRR rule is to require testing under ‘‘worst case’’ conditions from the standpoint of 

emissions and to establish parameters based on such testing that ensure compliance under all 

operating conditions. For example, in a response to comments on the original proposed subpart 

RRR rule regarding the inlet temperature requirement for fabric filters, the EPA stated that 

testing under worst case conditions, such as higher than normal fabric filter inlet temperatures, 

could provide a larger temperature operating range, which would be used to monitor and ensure 

continuous compliance between periodic performance tests (65 FR 15699, March 23, 2000). In 

the EPA response-to-comments document (Summary of Public Comments and Responses on 

Secondary Aluminum NESHAP, December 14, 1999, Docket No. A–92–61, item V–C–1, 

comment 4.1.47), the EPA explained that requiring multiple tests over a range of different 

furnace operating conditions will show that the selected monitoring parameters are valid 

indicators of emissions and that it may not be possible for a single test to be representative of 

worst case conditions and that more than a single test may be required. It is not permissible, for 

example, to demonstrate compliance while processing relatively uncontaminated scrap, and then 

at a later time, when the supply of this scrap is constrained, process more heavily contaminated 

scrap, without demonstrating compliance under these changed conditions based on previous 

emissions testing or on new emissions testing if previous tests would not be representative of the 

emissions from the processing of the more heavily contaminated scrap.

To clarify the requirements for testing, we proposed in the 2014 supplemental proposal that 

performance tests be conducted under representative (normal) conditions expected to produce the 

highest level of HAP emissions expressed in the units of the emission standards for the HAP 

(considering the extent of scrap contamination, reactive flux addition rate and feed/charge rate). 
47

If a single test condition is not expected to produce the highest level of emissions for all HAP, 

testing under two or more sets of conditions may be required, e.g., high contamination (or high 

reactive flux rate) at low feed/charge rate and low contamination (or low reactive flux rate) at 

high feed/charge rate. Other operating conditions may also affect the worst case test for one or 

more regulated HAPs. Any subsequent performance tests for the purposes of establishing new or 

revised parametric limits are allowed upon pre-approval from the permitting authority for major 

sources or the Administrator for area sources. These new parametric settings are used to 

demonstrate compliance for the period being tested. We solicited comment on whether the 

proposed amendment adequately addresses and clarifies the requirement that multiple tests may

be necessary to represent different operational conditions.

After considering the comments summarized above, we are adopting the rule amendment as 

proposed in the 2014 supplemental proposal, with the following exception. We agree with the 

commenter's contention that the parenthetical "normal" could lead to confusion and differing 

interpretations of the requirements for testing under conditions expected to produce the highest 

level of HAP (considering the extent of scrap contamination, reactive flux addition rate, and 

feed/charge rate), i.e., "worst case" emissions. The final rule does not contain the parenthetical 

"normal."

Comment #2: One commenter (0199) recommended that the EPA should clarify that because 

stack tests are designed to measure worst-case emissions, that when determining area source 

status, the emission factor determined during the stack test should be multiplied times the actual 

measured production rate achieved when the worst case material was processed during the stack 

test in the calculation of potential emissions. The commenter explained that if this is not done 

and the emission factor determined from a stack test performed when worst case materials are 

processed is combined with the highest production rate achieved processing the easiest material, 

the projected level of emissions will be much higher than is possible and area sources may

unfairly be made major sources.

Response: Area source status is generally determined by the potential-to-emit of the source (see 

definitions of area source and major source in 40 CFR 63.2). If the permitted annual production 

cannot be achieved while processing the highest-emitting type of material, then this may be 

taken into account in conducting an area source determination. In some cases, the capacity to 

process a greater throughput of a lower-emitting (on a per-unit-production basis) material may

result in a higher potential-to-emit. Absent an enforceable provision limiting emissions (for 

example, a limitation of the annual usage of reactive flux, or annual operating hours) or a 

physical limitation affecting potential to emit, potential-to emit determinations are based on the 

allowable emission rate.

Comment #3: One commenter (0192) on the 2012 proposal agreed with the new language the 

EPA is proposing for 40 CFR §63.1511(b)(1), stating that the language in the rule is 

appropriately broad so that testing of new flux materials, increasing the allowed furnace 

capacity, baghouse operating parameters and other operating parameters of the furnace could 

also be included. The commenter recommended that the EPA should clarify in the preamble to 

the final rule that other parameters can be changed during a performance test.
48

Response: Based on the comments received on the 2012 proposal and recognizing that it may be 

necessary to conduct performance tests under one or multiple scenarios to be representative of 

the range of normal operating conditions, we proposed revised language in 40 CFR 

63.1511(b)(1) in the 2014 supplemental proposal to clarify the conditions under which subpart 

RRR performance tests must be conducted. As we explained in the 2014 supplemental proposal, 

the intention is to require testing under “worst case” conditions from the standpoint of emissions 

and to establish parameters based on such testing that ensure compliance under all operating 

conditions. The final rule clarifies that performance tests be conducted under representative 

conditions expected to produce the highest level of HAP emissions expressed in the units of the 

emission standards for the HAP (considering the extent of scrap contamination, reactive flux 

addition rate and feed/charge rate). The final rule also allows additional performance tests for the 

purposes of establishing new or revised parametric limits upon pre-approval from the appropriate 

authority.

Comment #4: The commenter (0197) indicated that the EPA does not define “highest level of 

contamination” for scrap used in an initial performance test, so it is unclear what is intended and 

the requirement should be deleted in any event. The commenter indicated that process equipment 

could be put at risk of fire, explosion, or equipment damage since it was not designed to handle 

wet or heavily oiled chips. 

Commenter 0193 asked that the word “scrap” in §63.1511(b)(1) should be replaced with the 

words “feed/charge material” in that all aluminum containing material to be processed in a 

furnace may not be scrap. 

Commenters 0192, 0193, 0194 suggested that the phase “while an air pollution control device is 

operating” should also be deleted because all furnaces do not operate with an add-on control 

device.

Response: In response to the concern that process equipment could be put at risk of fire, 

explosion, or equipment damage if required to conduct a performance test using scrap it was not 

designed to handle, such as wet or heavily oiled chips, the rule does not require testing while 

processing a material that, because of safety considerations, would never be processed in the 

unit.

In the final rule, we have replaced the word “scrap” with the words “feed/charge” and have 

deleted the phrase “while an air pollution control device is operating” as suggested.

Comment #5: In a comment on the supplemental proposal, commenter 0294 stated that the 

EPA’s supplemental proposal addresses concerns previously articulated in their comments on the 

2012 proposal that relate to operating conditions during performance testing. The commenter 

stated that they support the EPA’s proposed revisions to the initial performance testing 

requirements at section 63.1511(b)(1).

Response: The EPA acknowledges the commenter’s support of the rule requirements for "worstcase" emissions scenario testing. As noted elsewhere in the response to comments, the only

change to section 63.1511(b)(1) after the supplemental proposal is the removal of the 

parenthetical "normal" from the first sentence of the paragraph (b)(1).
49

3.3 Reporting

Comment #1: One commenter (0193) objected to the proposed requirement to submit 

performance test reports electronically, because according to the commenter, it will impose a 

significant added financial burden on owners and operators of secondary aluminum smelters. 

The commenter asserted that the requirement constitutes double reporting and confidential 

business information may be jeopardized. The commenter requested that the EPA remove the

electronic reporting tool (ERT) language. 

Response: The EPA believes that any costs of using the ERT are reasonable and not burdensome 

for several reasons. The electronic reporting requirement does not add any additional testing or

change the timing of when test reports are due. The requirement only states that reports are to be 

submitted electronically. The ERT is fully functioning and has been used successfully by 

industry for several years. It was designed to capture all of the information which is submitted in 

a typical test report and was designed with input from States and the stack testing industry.

The EPA worked with State and local agencies as well as stack testing companies (who typically 

prepare test reports) to develop the ERT. The ERT was designed to accept data and information 

that is typically collected during a performance test. Some State and local agencies have begun 

accepting the ERT as their reporting mechanism and with experience we believe acceptance by

States will increase. In some instances state and local agencies may want a hard copy of a test 

report. The ERT can generate a printed test report or export the report to a word processor for 

reformatting. This report can be submitted to the State. The EPA believes that electronic 

reporting is a more efficient way to collect, store, and access test data and has set up a retrieval 

system such that States can access files that have been submitted using the ERT. As more States 

adopt electronic reporting, we believe that the need for paper reports will be diminished.

The commenter is incorrect that CBI would be jeopardized as a result of electronic reporting.

Facilities can submit CBI according to the EPA’s CBI procedures as always. The EPA will not 

make CBI publicly available, except in accordance with 40 CFR Part 2. In cases where some 

information in a test report is CBI, that information can be submitted separately as CBI.

Comment #2: The commenter (0197) noted that the Proposed Rule includes requirements for 

the submittal of reports in the records section (Proposed 40 C.F.R. § 63.1517(c)). The 

commenter also noted that the records section requires the source to “maintain” files and records, 

no reporting is required (40 C.F.R. § 63.1517(a) – (b)) and the first sentence of proposed section 

63.1517(c) contains a reference to the requirements in paragraph (b). The commenter indicated 

that it is not clear if paragraph (b) is in the records or reporting section. The commenter 

recommended that the proposed section 63.1517(c) should be moved to section 63.1516 which 

contains requirements for reporting, and the reference to requirements in paragraph (b) should be 

clarified.

Response: In the final rule, the reporting provision that was incorrectly placed in section 

63.1517 is now in the records section 63.1516, which also corrects the commenter’s concern 

with the reference to paragraph (b).
50

Comment #3: In a comment on the supplemental proposal, commenter 0301 stated that, rather 

than requiring just recordkeeping of important compliance data as the EPA proposes, the EPA 

should instead require electronic reporting of all key compliance data points, so that the EPA, 

state and local governments, and concerned community members can provide an additional 

check to assure compliance. The commenter stated that if a facility is creating a record, there is 

very little additional time needed simply to submit the record electronically, along with other 

reports, and the public-interest and deterrent value of doing so is substantial.

Response: While we agree that it would be preferable for all key compliance data be recorded 

and reported electronically, the EPA has not yet developed electronic reporting systems for all 

compliance data currently required by the EPA regulations. The EPA continues to develop these 

electronic reporting systems and will deploy them as they are ready.

3.5 Other

Comment #1: One commenter (0194) agreed with the EPA’s clarification for the daily SAPU 

emission limit calculation. The commenter noted that the commenter’s locations have actually

followed the proposed approach since the NESHAP became effective in 2003.

Response: The EPA acknowledges the commenter’s support.

Comment #2: In a comment on the supplemental proposal, commenter 0301 stated that they 

support the EPA’s proposal for annual inspection and improvements to compliance requirements.

Response: The EPA acknowledges the commenter’s support of the rule requirements that clarify

inspection and compliance requirements.
51

4. Compliance Dates

Comment #1: In a comment on the supplemental proposal, commenter 0296 stated that the 

compliance schedule in the supplemental proposal is much more reasonable than the compliance 

schedule in the 2012 proposal, allowing facilities an adequate window of opportunity for any

new technology additions to be researched, selected, purchase, financed and installed; it is also 

consistent with the 2 year compliance schedule in subpart ZZZZZZ.

Response: The EPA acknowledges the commenter’s support of the compliance dates.
52

5. Startup, Shutdown, and Malfunction

5.1 Removal of SSM Exemption

Comment #1: One commenter (0195) stated that the EPA does not have the authority to amend 

existing MACT standards to make them more stringent, as is being done by proposing the new 

SSM standards. The commenter argued that the EPA’s authority under CAA section 112(d)(6) is 

to “review and revise as necessary (taking into account developments in practices, processes, and 

control technologies), emissions standards promulgated under this section no less often than 

every 8 years.” The commenter observed that the EPA did not invoke its section 112(d)(6) 

authority to support the Proposed SSM Provisions, but even if it had, section 112(d)(6) does not 

provide broad authority to reconsider aspects of previously issued MACT standards unrelated to 

“developments in practices, processes, and control technologies.” The commenter maintains that 

the EPA cannot simply revisit and redo a MACT determination long after it has been issued, as

the EPA attempts to do with the Proposed SSM Provisions. The commenter argued that the EPA 

cannot change its mind about what standards are required to comply with CAA sections 

112(d)(2) and (3), nor can it recalculate a MACT floor based on subsequent performance.

The commenter asserted that reassessing existing NESHAP that were based on the MACT floor 

and imposing more-stringent requirements, would be inconsistent not only with the statute’s 

careful provision of technology-review and residual-risk authority to follow establishment of 

MACT standards, but also with Congress’ desire for finality evident in the judicial review of 

provisions of CAA section 307(b), which allows challenges to MACT standards within 60 days 

of promulgation. 

The commenter stated the EPA would have to justify why the decisions reflected in the current 

standards are wrong and why the new standards meet the required criteria that the EPA must 

satisfy in issuing MACT standards under CAA sections 112(d)(2) and (3). 

The commenter argued against the EPA’s interpretation of Sierra Club v. EPA, stating that the 

Sierra Club decision interpreted the NESHAPs General Provisions, not what the EPA may or 

may not include in source-category-specific MACT standards. 

The commenter stated that although the D.C. Circuit and the EPA referred to the provision 

vacated in the Sierra Club decision as an "exemption" from hazardous air pollutant standards 

during SSM events, other portions of the NESHAP General Provisions impose various 

requirements that apply to sources both during SSM events (including the obligation to minimize 

excess emissions) and in anticipation of and following SSM events (including requirements to 

prepare a plan to address SSM events and to report SSM events).

The commenter pointed out that opinions where the court was looking at source-category

specific MACT standards have emphasized the need for those standards to recognize and 

accommodate higher emission levels that occur at times other than normal operations. See, e.g., 

Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999).

The commenter asserted that the Sierra Club decision did not say that the same emission 

limitations that the EPA has derived for normal operations must also apply during SSM events. 
53

The commenter claimed that although an open-ended exemption from any standard under section 

112 is inconsistent with the Sierra Club holding that, for section 112 MACT standards, “there 

must be continuous section 112-compliant standards”, Sierra Club does not preclude the EPA 

from applying different standards during SSM events than apply during normal operations. The 

commenter argued that the opinion acknowledges that section 302(k)’s “inclusion of [the] broad 

phrase” “any requirement relating to the operation or maintenance of a source to assure 

continuous emission reduction” in the definition of “emission standard” suggests that the EPA 

can establish MACT standards consistent with CAA section 112 “without necessarily 

continuously applying a single standard.” 

The commenter stated that there is ample precedent for the EPA applying a different standard 

during SSM events. The commenter noted that language the D.C. Circuit considered dispositive 

in interpreting the EPA’s standard-setting authority under section 112 — the statement in the 

CAA section 302 definition of “emission limitation” and “emission standard” that it “limits the 

quantity, rate, or concentration of emissions of air pollutants on a continuous basis” — has been 

in the statute since 1977. The commenter observed that throughout that time, the EPA has not 

required sources to meet NSPS emission limitations under CAA section 111 established for 

normal operations during SSM events. 

The commenter noted that Congress enacted the “continuous basis” language in section 302(k) 

knowing that the EPA’s emissions standards under section 111 exempted SSM periods. The 

commenter argued that the “continuous basis” language inserted in 1977 is related to whether 

sources should be allowed to use temporary or intermittent pollution control technologies which 

entailed temporary reductions in emissions when weather conditions were poor, not what 

emission limitations apply during SSM periods, nor the EPA’s established practice of exempting 

excess emissions during SSM events from the performance standards applicable to normal 

operations. The commenter noted that the legislative history indicates Congress was aware that 

alternative emission limitations might at times be necessary, even though the emission 

limitations were established based on the capability of “continuous controls” like scrubbers. See, 

e.g., S. Rep. No. 94-717 at 78 (“It is recognized that the source controls may not be available to 

achieve the full reduction required of a particular source under particular circumstances. In such 

case, supplementary programs can and should be developed. But this flexibility occurs only after 

imposition of the continuous emission limitation.”).

The commenter asserted that the Sierra Club decision did not address whether the EPA could use 

a “design, equipment, work practice or operational standard,” as authorized under CAA section 

112(h) and included in the definition of “emission limitation” and “emission standard” in CAA 

section 302(k), in lieu of a numerical emission limitation during SSM events. The commenter 

stated that the EPA told the Court that the General Provisions SSM exemption struck down in 

Sierra Club was not an alternative standard based on the work practice standard authority. The 

commenter noted that the EPA argued in that case that section 112(h) was irrelevant to its 

authority to exempt excess emissions during SSM events. 

The commenter maintained that the EPA cannot use the Sierra Club decision as a justification 

for ignoring an inability of even the “best performers” to achieve during SSM events the

emission limitations the EPA has established for normal operations. The commenter asserted that 

the approach the EPA is proposing would not establish “continuous section 112-compliant 
54

standards” that the Sierra Club decision concluded are required, as MACT emission standards 

must be “achievable.” The commenter stated that an emission limitation that applies during SSM 

events does not meet the requirement of CAA section 112(d)(2) that “emission standards” under 

that section be “achievable” if in fact the EPA has not demonstrated that the limitation is 

“achievable” with available technology. The commenter argued that an emission limitation that 

applies during SSM events has not been demonstrated to be “achieved” by the best-performing 

12% of units in the category under CAA section 112(d)(3) unless the EPA can show that those 

best performers actually meet that emission limitation during SSM events. The commenter 

asserted that the EPA has not demonstrated that the emission limitations in the existing MACT 

standards, if they also applied during SSM events, would comply with section 112 when applied 

to SSM periods.

The commenter argued that the courts have long recognized that a “technology based standard 

discards its fundamental premise when it ignores the limits inherent in technology.” NRDC v. 

EPA, 859 F.2d 156, 208 (D.C. Cir. 1988). The commenter provided examples. The D.C. Circuit 

recognized, in Portland Cement Ass'n v. Ruckelshaus, 486 F.2d 375, 398 (D.C. Cir. 1973), a 

decision reviewing standards under CAA section 111, that “‘start-up’ and ‘upset’ conditions due 

to plant or emission device malfunction, is an inescapable aspect of industrial life and that 

allowance must be made for such factors in the standards that are promulgated.” In Essex Chem. 

Corp. v. Ruckelshaus, 486 F.2d 427, 432 (D.C. Cir. 1973), another section 111 case, the court 

held that SSM provisions are “necessary to preserve the reasonableness of the standards as a 

whole.” In National Lime Ass’n v. EPA, 627 F.2d 416 (D.C. Cir. 1980), another case reviewing 

emission standards promulgated under CAA section 111, the court held that the CAA 

requirement that NSPS be “achievable” means that the standards must be capable of being met 

“on a regular basis,” including “under most adverse circumstances which can reasonably be 

expected to recur,” including during periods of SSM. 

The commenter cited cases in support of the commenter’s argument related to the Clean Water 

Act. 

The commenter stated that Weyerhaeuser Co. v. Costle, 590 F. 2d 1011 (D.C. Cir. 1978), does 

not support the EPA’s position. The commenter asserted that in that case, the court was 

discussing a “technology forcing” standard, rather than one, like MACT, that is to be based on 

what is already being “achieved” or has been demonstrated to be achievable. The commenter 

claimed that the SSM events that the EPA acknowledges are expected to occur at sources subject 

to the Proposed Standards are a far cry from the unusual “’uncontrollable acts of third parties,’ 

such as strikes, sabotage, operator intoxication, or insanity” that the court was considering in the 

passage quoted by the EPA. The commenter stated that industry is not requesting that the MACT 

standards provide relief from numerical emission limitations during those unusual types of 

events. The commenter emphasized that the Weyerhaeuser decision came long before NRDC v. 

EPA, 859 F.2d 156 (D.C. Cir. 1988) which, as noted above, affirmed the need for an upset 

provision to address circumstances where compliance with effluent limitations is impossible 

through no fault of the permittee, and which endorsed Marathon Oil.

The commenter noted that the EPA acknowledges this precedent in the rule preamble, but 

suggests that “intervening case law such as Sierra Club v. EPA and the CAA 1977 amendments 

undermine the relevance of these cases today.” However, the commenter maintained that the 
55

EPA does not explain why it believes that to be the case. According to the commenter, Sierra 

Club v. EPA did not address this precedent, and the 1977 CAA amendments if anything support 

the conclusion that emission standards need to deal with the inability of a source to meet the 

normal emission limitations during particular circumstances. The commenter argued that the 

National Lime Ass’n decision, which relies in part on the cases the EPA referenced in the 

preamble, and which directly addresses the need for emission limitations that address reasonably

anticipated adverse circumstances, post-dates the Clean Air Act Amendments of 1977 by three 

years.

The commenter pointed out that the Sierra Club decision rejected the EPA’s asserted discretion 

to not to impose any emission standard covering SSM periods. The commenter asserted that the 

Sierra Club decision expressly recognized that different standards, including non-numerical 

standards, may (and in some cases must) apply during non-standard operating conditions, such as 

SSM events. The commenter added that the statement in the majority opinion that “Congress 

gave no indication that it intended the application of MACT standards to vary based on different 

time periods” is contradicted by other statements in the opinion that a MACT standard need not 

continuously apply a single emission limitation, is dicta because that was not the situation 

presented by the challenged regulations and argued by the EPA, ignores the extensive case law 

about technology-based limitations referenced above, and does not in any event say that the 

CAA precludes the EPA from adopting different emission limitations that apply during SSM 

events.

One commenter (0195) disputed EPA’s approach to malfunctions is consistent with CAA section 

112 and is a reasonable interpretation of the statute. The commenter observed that the EPA says 

it “has determined that CAA section 112 does not require that emissions that occur during 

periods of malfunction be factored into development of CAA section 112 standards,” which the 

commenter maintains the EPA makes little effort to justify. The commenter disagreed with the 

EPA’s statement that “[t]here is nothing in CAA section 112 that directs the agency to consider 

malfunctions in determining the level ‘achieved’ by the best performing or best controlled 

sources when setting emission standards,” claiming that there is nothing in CAA section 112 that 

allows EPA to ignore malfunctions and set MACT standards based on a level of emissions that 

even best-performing sources only achieve part of the time. The commenter asserted that EPA’s 

rationale for not factoring in malfunctions directly contravenes congressional intent that MACT 

floor standards be based on what the best sources actually achieve.

The commenter recommended that the EPA to use authority under CAA section 112(h) to 

prescribe alternative design, equipment, work practice or operational standards where it is not 

feasible to set or enforce a numerical emission limit. The commenter disagreed with EPA’s view 

that applying the concept of “best performing” is inconsistent with a source experiencing a 

malfunction. The commenter asserted that there are work practices – such as monitoring of 

operating parameters to identify a malfunction and stopping or cutting back the process 

accordingly – that represent the best practices for minimizing emissions during a malfunction, 

and these best practices represent the "the maximum degree of reduction in emissions of the 

hazardous air pollutants...achievable...through application of measures, processes, methods, 

systems or techniques" and reflect "the emission control that is achieved in practice by the best 

controlled similar source[s]".
56

One commenter (0195) asserted that the EPA’s historical definition of “malfunction” is not in 

any way binding on how EPA defines the events that the Agency will refuse to take into 

consideration when establishing MACT emission standards. The commenter stated that by acting 

as if it were binding on EPA standard-setting, EPA has proposed a perverse approach to 

establishing emission standards in which the more common a situation is that results in higher 

emissions than normal operations, the less likely it is that EPA will write emissions standards to 

take that situation into account—either in the standards themselves or in the affirmative defense.

One commenter (0195) stated that the elimination of SSM provisions in the existing MACT 

standards would put operators in a Catch-22 situation: the NESHAP would no longer 

accommodate the excess emissions that EPA knows will occur regularly during normal plant 

operations, due to process variability and control equipment operations and availability, yet those 

same events would appear to be ineligible for the “affirmative defense” that EPA proposes as a 

means of addressing excess emissions that occur despite a source’s proper design and operation, 

because the “affirmative defense” is only available for excess emissions that result from 

“infrequent” events that cannot be “foreseen...and planned for.” The commenter asserted that for 

the EPA to finalize these proposed actions would be unreasonable, arbitrary and capricious, and 

not in any way required by the Clean Air Act or judicial precedent.

One commenter (0195) stated that EPA ignores the undisputed existence of malfunctions even at 

best-performing sources, and the EPA claims falsely that the best-performing sources “achieve” 

emission levels that they undisputedly do not achieve part of the time. The commenter disagreed 

with the EPA’s conclusion that malfunction events are not representative of best-performing 

sources. See, e.g., Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 862-865 

(D.C.Cir.2001) (recognizing that there is variability in the performance of control technologies, 

which needs to be accounted for in establishing emission limitations based on the MACT floor); 

Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999). The commenter observed that one goal 

of best performing sources is to operate in such a way as to avoid malfunctions, but the 

commenter believes that that is all the more reason for the EPA to acknowledge that those 

sources experience malfunction events. 

One commenter (0195) asserted in regard to malfunction events, that by proposing MACT 

standards that EPA recognizes even the best performing existing sources cannot achieve part of 

the time, EPA is going beyond the MACT floor, yet without making the demonstrations that the 

statute and case law require the Agency to make in order to impose beyond-the-floor MACT 

standards. The commenter claimed that the EPA has not justified as reasonable the conditions 

that the EPA proposes to impose on sources during malfunctions in order to be excused from 

civil penalties “taking into consideration the cost of achieving such emission reduction, and any 

non-air quality health and environmental impacts and energy requirements....” 

The commenter stated that it is indefensible for EPA to acknowledge that malfunctions are 

inevitable, even for the best performing sources, and yet refuse to include emissions data 

representing malfunctions (if such data exist) in calculating the MACT floor, and then require 

that those MACT floor limitations be met even during malfunctions. The commenter asserted 

that the EPA is obligated to consider representative data reflecting emissions during 

malfunctions in its MACT floor calculations for steady-state operating conditions, if that data 

can be gathered. 
57

The commenter recommended that to the extent EPA had access to continuous monitoring data 

for emission units covered by the NESHAP, EPA could have conducted analyses of emissions 

levels during malfunction events. The commenter noted that even if the continuous monitoring 

data are for parameters not regulated by the Proposed Standards, analysis of monitoring data for 

those other parameters during malfunction events might form a reasonable basis for EPA’s 

assessment of what standards are achieved or achievable during malfunctions. The commenter 

suggested that many types of sources are required by many state agencies to submit deviation 

reports or malfunction reports when they experience a malfunction that causes an exceedance of 

an applicable limitation. The commenter observed that the EPA does not appear to have made 

any attempt to obtain and analyze such reports, in order to assess what type of requirement might 

reasonably apply to the subject emission units during malfunctions.

The commenter offered several options for setting MACT standards under CAA section 112 that 

would apply during malfunction events:

• Establish an emission limitation that applies at all times, but that has an averaging time of 

sufficient duration that short, infrequent spikes in emissions due to malfunctions would not cause 

the source to exceed the emission limitation (while at the same time ensuring that the source does 

not operate in a way that causes frequent, lengthy excursions above the normal controlled 

emission rate);

• Use the flexibility accorded by CAA section 302(k) (defining “emission limitation” and 

“emission standard” to include “any requirement relating to the operation or maintenance of a 

source to ensure continuous emission reduction, and any design, equipment, work practice or 

operational standard promulgated under” the CAA) to address emissions during malfunction 

events through operational requirements rather than by applying the same limits on pollutant 

concentrations in exhaust gases that apply during normal operations; and/or

• Promulgate under CAA section 112(h) a design, equipment, work practice, or operational 

standard, or combination thereof, because it is not feasible to prescribe or enforce an emission 

standard.

The commenter stated that the EPA did not consider any of these types of options, and the lack 

of evaluation of these options renders the Proposed Rule arbitrary, and requires EPA to develop a 

new proposal.

One commenter (0193) disagreed with the EPA’s proposed approach for regulating 

malfunctions, stating that it is unjust and creates a legal dilemma for owners/operators to be 

accused of exceeding unachievable emission standards due to events outside their control. One 

commenter (0194) expressed concern that the EPA, recognizing that malfunctions are not all 

reasonably preventable, creates a legal dilemma for owners/operators to be accused of exceeding 

unachievable emission standards due to events outside their control.

For technology-based standards, a commenter (0197) noted that EPA and courts have recognized 

that EPA must either (a) consider SSM in setting the standards or (b) provide an upset defense. 

The commenter indicated that EPA should revise its SSM provisions.
58

Commenter 0298 on the 2014 supplemental proposal (same as commenter 0195 on 2012 

proposal) stated when EPA ignores emissions that even best-performing sources experience 

during malfunctions, EPA breaches its duty to set standards on the basis of real-world 

performance; it fails to take into account how sources actually operate and unlawfully prohibits 

emissions that cannot be avoided. See, e.g., Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 

1999) (a best-performing source should not violate a standard supposed to be based on what it 

“achieve[s] in practice”); see also 76 Fed. Reg. 15628 (rejecting a comment as “inappropriate” 

because it “would result in emission limits that even the best performing sources would be 

expected to exceed”). The commenter stated that every court that has addressed the issue, both 

under the CAA section 111 requirement that new source performance standards be based on the 

best demonstrated control technology and under the similar technology-based requirements of 

CAA section 112(d) and (h), has indicated that EPA must take the effect of malfunctions on 

emissions into account when establishing such technology-based emission standards. See 

Portland Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 398-99 (D.C. Cir. 1973); Essex Chemical 

Corp. v. Ruckelshaus, 486 F.2d 427, 432 (D.C. Cir. 1973); Nat’l Lime Ass’n v. EPA, 627 F. 2d 

416, 431 (D.C. Cir. 1980); Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855, 872 (D.C. 

Cir. 2001); NACWA v. EPA, 734 F.3d 1115, 1158 (D.C. Cir. 2013) The commenter stated that 

while EPA may be implying in the supplemental notice that the opportunity that a source would 

have to argue to a court in an enforcement action that a malfunction justifies a reduced or no 

penalty, is a satisfactory means of accommodating the effect of malfunctions on what standards 

are achievable with available technology, the statute directs EPA to set standards based on what 

the available technology can do or, in the case of MACT floor standards, based on what the best 

performers are actually doing. The commenter stated that nothing in the statutory language or 

legislative history indicates that Congress intended EPA to establish MACT standards that apply 

at all times, but that even best performers cannot meet during unavoidable malfunctions, and 

then have penalties potentially mitigated in an enforcement action. According to the commenter, 

courts agree with this analysis, stating repeatedly that relying on enforcement discretion is no 

substitute for setting technology-based standards that reflect the performance of that technology

during all reasonably anticipated conditions. See, e.g., Portland Cement, 486 F.2d at 398 n.91; 

Nat’l Lime, 627 F. 2d at 431 n.46; Marathon Oil Co. v. EPA, 564 F.2d 1253, 1273 (9th Cir. 

1977). The commenter stated that, moreover, the enforcement discretion approach does not 

satisfy the purpose of CAA section 112 of reducing HAP emissions; a post-hoc case-by-case 

evaluation of emission circumstances, as EPA intends to handle all malfunction periods, will not 

prevent or reduce emissions of HAPs. The commenter stated that rather than the starting point 

being affirmative steps to prevent emissions as Congress intended (including steps that would 

have been encouraged by the conditions specified in the affirmative defense), the starting point 

for the approach in the supplemental notice is the post-emission presumption of wrongdoing by 

the source operator.

Commenter 0298 stated that EPA has tools for accounting for malfunctions in the standards once 

the affirmative defense is eliminated. The commenter stated that the supplemental notice repeats 

EPA’s conclusory statements in the proposed rule that it would be too difficult for EPA to 

consider malfunctions when establishing emission standards and that doing so would result in 

standards that are too lenient. According to the commenter, the court decision that EPA cites, 

Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), specifically acknowledged that EPA has 

authority under the CAA to set different standards that apply at different times, so long as some 

CAA section 112 compliant standard applies at all times and EPA has used that authority in 
59

numerous rulemakings to set alternative emission standards that apply during startup and 

shutdown periods. The commenter stated that there is nothing in EPA’s mandate to set emission 

standards allows EPA to decline to even assess whether it has sufficient data, or can obtain 

sufficient data, to set numerical limitations that apply during malfunction events. The commenter 

stated that EPA also can use sections 112(h) and 302(k) to substitute a design, equipment, work 

practice, or operational standard for a numerical emission limitation; the use of work practices 

will in most cases be more practicable and more comprehensive than trying to establish 

numerical standards to address all malfunctions. The commenter stated that one approach that 

has proven effective in the past is to specify the elements and objectives of a plan that the source 

must develop, follow, and review to assure that the source is taking the appropriate steps before, 

during, and after a malfunction to minimize excess emissions; it is likely that most if not all or 

the sources identified as best performers have such plans and follow them to responsibly address 

malfunctions. The commenter stated that EPA has already shown that it can use work practices 

when a source is operating in other than normal steady-state operation, when EPA established 

work practice standards in lieu of numerical emission limitations for numerous source categories 

that apply during startup or shutdown. The commenter stated that before EPA promulgates 

revised emission standards for secondary aluminum plants that apply even during malfunctions 

but that contain no affirmative defense or other provision addressing malfunctions, EPA should 

determine an appropriate set of work practices, or a combination of work practices and 

alternative numerical emission limitations, that address higher emissions associated with 

malfunctions of properly designed and operated MACT technology, and EPA must offer its 

analysis for public comment before finalizing the deletion of the affirmative defense and the 

adoption of the alternative standards.

Response: The EPA disagrees in many ways with the commenters, first in that the EPA does not 

lack authority to make the changes proposed. We specifically disagree with the commenter’s 

suggestion that Sierra Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008) is not relevant because it 

addressed the SSM exemption in the General Provisions rather than source category-specific 

MACT standards. The holding in Sierra Club that emissions limitations under section 112 must 

apply continuously and meet minimum stringency requirements, even during periods of startup, 

shutdown and malfunction, is clearly applicable to source category-specific MACT standards. As 

we explained in the 2012 and 2014 proposals, our SSM-related rule revisions are in response to 

the Sierra Club court’s vacature of the SSM exemption in §§63.6(f)(1) and 63.6(h)(1). 77 FR at 

8598-8600. When incorporated into section 112(d) regulations for specific source categories, 

these two provisions exempted sources from the requirement to comply with otherwise 

applicable MACT standards during periods of SSM. Subpart RRR, Appendix A incorporated 

several General Provisions related to SSM, specifically including §§63.6(f)(1) and 63.6(h)(1). 

The court’s vacature rendered those provisions null and void prior to this rulemaking. The 

mandate implementing the court’s decision was issued on October 16, 2009, at which time the 

vacated SSM provisions were clearly no longer in effect, and standards in subpart RRR applied 

at all times, including periods of SSM. The rule changes to remove the vacated SSM provisions 

from subpart RRR are ministerial actions by the EPA to reflect the vacature by the court. 

In addition, in Medical Waste Institute v. EPA, 645 F. 3d 420, 425-27 (D.C. Cir. 2011), the D.C. 

Circuit Court held that EPA may permissibly amend improper MACT determinations, including 

amendments to improperly promulgated floor determinations, using its authority under section 

112(d)(2)-(3). In light of the court decisions in Sierra Club and National Lime Ass'n v. EPA, 233 
60

F.3d 625, 633-34 (D.C. Cir. 2000), the exemption from standards in Subpart RRR for HAP 

emitted during SSM was not proper. Similarly, the Court’s decision in Portland Cement Ass’n v. 

EPA, 665 F.3d 177, 189 (D.C. Cir. 2011) confirms that although 112(d)(6) requires EPA to 

reassess its standards every eight years, nothing prohibits it from doing so more often, including 

revising existing floors if need be. The commenter is thus incorrect that EPA lacks authority to 

amend promulgated MACT standards or that section 112(d)(6) provides exclusive authority to 

address standards that apply during SSM. 

We are not adopting different standards for periods of startup and shutdown, although we do not 

claim that the Sierra Club decision constrains our authority to set different standards, including 

work practice standards under section 112(h), for SSM periods. Instead we are applying the 

existing Subpart RRR MACT standards to periods of startup and shutdown because the scrap 

processed at secondary aluminum production facilities is the source of emissions, and we expect 

emissions during startup and shutdown to be no higher, and most likely significantly lower, than 

emissions during normal operations since no scrap is processed during startup and shutdown

periods. We stated in the preamble to the 2012 proposed rule that we knew of no reason why the 

existing MACT standards should not apply at all times, and we have received no information to 

change that conclusion. For additional responses to comments concerning standards during 

periods of startup and shutdown and alternative methods for demonstrating compliance with 

production-based limits, see the discussion in section 5.2 below.

The EPA also disagrees with the commenter’s suggestion that the existence of an SSM 

exemption in rules implementing section 111 in 1977 when Congress enacted the “continuous 

basis” language in the definition of “emission standard” is evidence that Congress approved of 

that regulatory SSM exemption. We do not believe the legislative history cited supports that 

Congress was aware or approved of that exemption. 

The commenters assert that the EPA must account for malfunctions when determining the 

emissions level achieved by the best performing sources, but this view is neither reasonable nor 

supported by the text of the CAA. A malfunction is defined as a “sudden, infrequent, and not 

reasonably preventable failure of air pollution control and monitoring equipment, process 

equipment or a process to operate in a normal or usual manner * * *” (40 CFR 63.2). The EPA 

interprets CAA section 112 as not requiring emissions that occur during periods of malfunction 

to be factored into development of CAA section 112 standards. Under CAA section 112, 

emissions standards for new sources must be no less stringent than the level “achieved” by the 

best controlled similar source and for existing sources generally must be no less stringent than 

the average emission limitation “achieved” by the best performing 12 percent of sources in the 

category. There is nothing in section 112 that directs the Agency to consider malfunctions in 

determining the level “achieved” by the best performing sources when setting emission 

standards. As the D.C. Circuit has recognized, the phrase “average emissions limitation achieved 

by the best performing 12 percent of” sources “says nothing about how the performance of the 

best units is to be calculated.” NACWA v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). In 

addition, accounting for malfunctions in setting emission standards would be difficult, if not 

impossible, and could lead to standards that are not reflective of levels achieved by a wellperforming non-malfunctioning source. The EPA’s approach to malfunctions is a reasonable 

interpretation of the statute. If a source fails to comply with the applicable CAA section 112 

standards as a result of a malfunction event, as discussed above, the EPA would determine an 
61

appropriate response, and the source can raise any and all defenses in any enforcement action 

that may be filed.

The EPA’s approach both accounts for variability associated with a reasonably foreseeable range 

of operating conditions and recognizes that enforcement mechanisms can address emission 

exceedances due to unpreventable equipment or process failures. While commenters may seek 

greater accommodation for malfunctions, such accommodation is not compelled by the Act.

Unlike start-up and shut-down, which are foreseeable operations, no one can predict the nature, 

scope, severity, timing, length, number or likely recurrences of malfunctions a source may – or 

may not – experience. Although the EPA bases emission standards on different manners of 

operations and circumstances, the EPA only takes into account conditions that are “foreseeable” 

and “which can reasonably be expected to recur.” Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. 

Cir. 1999); see also Nat’l Lime Ass’n v. EPA, 627 F.2d. 416, 431 n.46 (1980). Virtually no 

malfunction is foreseeable in terms of its nature, timing or effect on emission levels and no 

operator knows if or when a malfunction could recur.

The commenters identify no language in the statute that even implies that EPA must factor into 

MACT emission standards the emission levels that occur during malfunctions. Yet the 

commenters assert that CAA section 112 mandates that EPA account for malfunctions in 

establishing every MACT standard or set a separate MACT standard for malfunctions, so that 

they reflect higher emission levels that might occur during undefined, unidentified malfunction

events. The commenters appear to rely on the silence of section 112, which does not speak 

directly to how malfunctions are to be treated to support their view, filling the void with the 

commenters’ own judgments of how EPA must address such uncertain and undefined events.

Although EPA may have authority to address malfunctions through different mechanisms –

albeit limited by the Court in Sierra Club v. EPA (striking down exemptions for malfunctions) 

and NRDC v. EPA (striking down an affirmative defense for malfunctions) – EPA is not 

required by section 112 to account for malfunction emissions by resetting MACT standards (e.g., 

with long averaging times) or by setting separate MACT standards (e.g., work practice 

standards) as suggested by the commenter.

A commenter asserts that relying on case-by-case enforcement discretion to address violations 

caused by malfunctions does not satisfy the purpose of CAA section 112 of reducing HAP 

emissions because it will not prevent or reduce emissions. We disagree. Applying the existing 

Subpart RRR MACT emission standards at all times meets the Act’s purpose in section 112 and, 

as enforceable emission standards, limits HAP emissions in accordance with the Act. The 

commenter states that enforcement discretion is no substitute for accounting for malfunctions in 

the standards themselves and suggests that different standards or requirements could be applied 

to malfunction events. As discussed above, we are not required to account for malfunction 

emissions in section 112 standards, and based on the information available to EPA concerning 

compliance by sources with Subpart RRR standards, we find no reason to do so.

A commenter contends that section 112 mandates that EPA establish MACT standards so that 

they reflect higher emission levels that might occur during unidentified, unmeasured malfunction 

events. To support its argument, the commenter states that emission limitations must be 
62

“achieved in practice”. The commenter asserts that the EPA has failed to develop standards that 

are “achieved in practice” if the best performing sources are expected to have malfunctions, and 

those malfunctions result in emissions that exceed the standard. But a source that suffers worker 

malfeasance or experiences a hurricane or a terrorist event may also exceed emission standards at 

certain times. These events, like malfunctions, do not transform achievable standards into 

unachievable standards. Indeed, under the commenter’s reasoning, every MACT standard is 

potentially invalid because it does not reflect emission levels that may occur during the next 

malfunction, act of God, strike, malfeasance or other unpredictable event.

Hurricanes and malfeasance can occur at well-maintained and well-managed sources and can 

cause upset conditions that result in violations of emission standards, but this does not warrant 

factoring such unpredictable events into revised emission standards. Even if malfunctions were 

inevitable for all sources, including the best-performing sources, that does not make it possible to 

take them into account when establishing MACT emission standards, because they are still 

unknown in frequency, length, magnitude and, most importantly, effect on emission levels.

The commenter asserts that the EPA inappropriately relies on the CWA case Weyerhaeuser Co. 

v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) because the Weyerhaeuser court based its 

holding on the fact that the standards at issue there were technology-forcing. While the Court did 

address this point, it went on to uphold EPA’s case-by-case enforcement discretion approach to 

addressing malfunctions because interjecting factors dependent on “murky determinations 

concerning the sequence of events in the plant, whether those events would have been avoidable” 

and similar factors, is inconsistent with the intent of Congress to require numeric emission 

standards that are measurable and easily enforceable. 590 F.2d at 1057-58. The commenter also 

argues that the Weyerhaeuser decision only addressed effects from “uncontrollable acts of third 

parties” which are “a far cry” from events that would occur under Subpart RRR. In fact, the 

Court in Weyerhaeuser was addressing “unusual events such as plant start-up and shut-down, 

equipment failures, human mistakes, and natural disasters.” 590 F.2d at 1056.

The commenter implies that Weyerhaeuser was overruled by another Clean Water Act case, 

NRDC v. EPA, 859 F.2d 156 (D.C. Cir. 1988), citing it for the proposition that a technologybased standard must accommodate defects in technology. That case was decided in 1988, long 

before the court decisions that found an exemption and an affirmative defense for malfunctions 

were contrary to the requirements of the Act. Moreover, the discussion of technology-based 

standards in the NRDC decision was dicta. The holding in NRDC was that water quality based 

standards do not need to account for malfunctions despite sources’ use of technology for 

compliance. Although Congress revised the HAPs program in 1990 to have technology serve as 

the core for establishing emission standards, those standards are also not strictly control 

technology-based but rather are based on the emission levels actually achieved in practice, which 

the Court has explained goes beyond what can be achieved solely through available control 

technology. See Sierra Club v. EPA, 479 F.3d 875, 882-83 (D.C. Cir. 2007).

The commenter also offers the decision in Cement Kiln Recycling Coalition v. EPA to support 

its argument that malfunctions must be considered in developing emissions standards. However, 

nothing in Cement Kiln even implies that EPA has a duty to reflect in its emission standards 

emission levels that might occur during unpredictable malfunction events. To the contrary, 

Cement Kiln cuts to the heart of commenters’ argument. The fundamental principle of the 
63

commenters’ argument is that due to malfunctions, the MACT emission standards, which have 

been achieved by secondary aluminum production facilities, may be “unachievable” if specific

sources experience a malfunction (citing Cement Kiln Recycling Coalition v. EPA, 255 F.3d 

855, 872 (D.C. Cir. 2001); Sierra Club v. EPA, 167 F.3d 658, 665 (D.C. Cir. 1999); Portland 

Cement Ass’n v. Ruckelshaus, 486 F.2d 375, 398-99 (D.C. Cir. 1973); Essex Chemical Corp. v. 

Ruckelshaus, 486 F.2d 427, 432 (D.C. Cir. 1973); Nat’l Lime Ass’n v. EPA, 627 F. 2d 416, 431 

(D.C. Cir. 1980); NACWA v. EPA, 734 F.3d 1115, 1158 (D.C. Cir. 2013)). The Court in Cement 

Kiln, however, rejected the notion that because a MACT standard may not be achievable by

some sources, it is invalid. Cement Kiln, 255 F.3d at 861 (“EPA may not deviate from section 

7412(d)(3)’s requirement that floors reflect what the best performers actually achieve by 

claiming that floors must be achievable by all sources using MACT technology.”). See also 

Sierra Club v. EPA, 479 F.3d at 878; NACWA, 734 F.3d at 1150 (explaining that the argument 

that a MACT standard is invalid because it is not achievable by all sources at all times has been 

“roundly rejected” by the Court).”

Comment #2: One commenter (0195) argued that the EPA’s proposal to replace §63.6(e)(1) 

with the somewhat different “general duty” language in proposed sections 63.1506(a)(5) and 

63.1520(a)(8) is not being proposed under CAA section 112(d)(6) or 112(f), and the EPA 

therefore lacks authority to make this change to the existing RRR NESHAP. The commenter 

disagreed with the EPA’s statement that the proposed sections 63.1506(a)(5) and 63.1520(a)(8) 

replace General Provisions requirements that reference vacated SSM provisions. The commenter 

stated that the D.C. Circuit did not vacate the provision the EPA proposes to replace, §63.6(e)(1), 

in Sierra Club v. EPA (which vacated the “exemption” for SSM events in sections 63.6(f)(1) and 

(h)(1), not the requirement for good air pollution control practices), and, contrary to the EPA’s 

assertion in the preamble to the Proposed Rule, §63.6(e)(1) does not reference provisions that 

were vacated in Sierra Club v. EPA.

The commenter maintained that even if the EPA had authority to change the existing MACT 

standards in ways not required to address residual risk or new technology, the Agency would 

have to provide a cogent explanation of why the old rule was unacceptable and the new rule is 

necessary, which the commenter claimed the EPA has not done.

The commenter recommended that the EPA delete proposed section 63.1506(a)(5) from the final 

rule, but if the EPA does not delete the proposed section, the commenter recommended that the 

EPA re-propose the provision with some explanation of the basis and purpose for the provision, 

to allow the public an opportunity to provide meaningful comments, as required by CAA section 

307(d)(3).

Response: The EPA disagrees with the commenter, in that the EPA does not lack authority to 

make the changes proposed (see response to comment #1 above). The EPA explained in the 2012 

proposal that we were proposing to add language to this regulation to replace General Provision 

requirements that reference vacated SSM provisions. 77 FR at 8597, 8598-8600. We are revising 

the general duty language because some of the language in that section is no longer necessary or 

appropriate in light of the elimination of the SSM exemption. Specifically, the prior language in 

63.1506(a)(5) and 63.1520(a)(8) characterized what the general duty entails during periods of 

SSM. With the elimination of the SSM exemption, there is no need to differentiate between 

normal operations, startup and shutdown, and malfunction events in describing the general duty.
64

Sources will be subject to emission standards at all times, including during periods of startup and 

shutdown and malfunction, and other language in the final rule already makes clear that the 

general duty to minimize emissions applies at all times. Therefore, there is no need to specify

that malfunctions need to be corrected as soon as possible or to further specify the application of 

the general duty requirement during periods of SSM. Our notice of proposal was sufficient on 

this topic and the rule revisions do not need re-proposal.

Comment #3: One commenter (0195) maintained that even if the EPA could legally go back and 

change the existing MACT standards, it could not reasonably make those revised standards 

effective immediately. According to the commenter, sources subject to the Proposed Rule would 

be expected to comply with revised SSM requirements as soon as the rule becomes effective. 

The commenter argued that it would be arbitrary and capricious for the EPA to require 

compliance immediately, when CAA section 112(i) allows a compliance deadline of up to three 

years. The commenter observed that elimination of the SSM provisions in the existing rules 

could require plants to make significant changes to their production processes or their HAP 

collection and control systems, which would take significant time for design, engineering, 

acquisition, and installation. 

Response: We disagree that we lack justification for making rule changes to remove the vacated 

SSM provisions effective upon promulgation. As discussed above, the D.C. Circuit Court’s

vacature of SSM provisions in its Sierra Club decision rendered those provisions null and void 

prior to this rulemaking. EPA issued a letter dated July 22, 2009 from Adam Kushner, Director, 

Office of Civil Enforcement, to various parties that addressed the impact of the decision in Sierra 

Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008). The mandate implementing the court’s decision 

was issued on October 16, 2009, at which time the vacated SSM provisions were clearly no 

longer in effect, and standards in subpart RRR applied at all times. The rule changes to remove 

the SSM provisions from subpart RRR are ministerial actions by EPA to reflect the vacature by 

the court. In addition, amendments to subpart RRR were proposed on February 14, 2012, at 

which time secondary aluminum plants were put on notice of the specific wording changes to 

subpart RRR. Thus, facilities have had ample notice of the SSM rule changes.

5.2 Startup and Shutdown

Comment #1: Commenters (0193, 0194) suggested that the entire paragraph at 

§63.1516(b)(1)(v) in the current Subpart RRR rule needs to be deleted. The commenters noted 

that this paragraph refers to actions taken under a startup, shutdown and malfunction (SSM) plan, 

and the proposed rule removes SSM Plan requirements. 

Response: The commenter is correct and this paragraph has been deleted.

Comment #2: Commenters (0193, 0194, 0197) stated that the EPA has not evaluated or justified 

applicability of the existing MACT emission limits to startup, shutdown or malfunction periods. 

The commenters noted that the current MACT limits are based on performance tests conducted 

during normal process operation, not during SSM periods. Commenter 0192 noted that current 

work practices used by the industry during startup and shutdown of batch-operated furnace are 

adequate and regulatory requirements are not necessary.
65

Commenters (0192, 0199) asserted that the EPA’s 2012 proposal to use the feed rate determined 

in the performance test to calculate production normalized emission rates during startup and shut 

down is inappropriate. The commenters explained that during startup and shutdown periods, little 

or no amount of aluminum is in a batch-operated conventional melting furnace, and thus no 

aluminum smelting-related emissions. The commenters observed that the zero production 

number during those startup and shutdown periods creates mathematical problems when 

calculating pounds per ton or micrograms per megagram production normalized emissions.

One commenter (0195) stated that the commenter’s members do not have sufficient information 

to comment on whether in fact the emissions during startup and shutdown of the sources subject 

to the 2012 proposed rule will be no greater than emissions during normal operations, but 

expressed the opinion that the EPA has not adequately justified this conclusion. The commenter 

cited the possibilities that a control device may be less efficient until it reaches its design 

operating temperature, it may be less efficient when the pollutant concentrations in the gases to 

be treated are lower than during steady-state operation, or until a manufacturing process reaches 

steady-state operation, that process may generate substantially higher emissions, either on a totalmass basis or on a mass-per-unit-of-production basis.

The commenter suggested that the EPA conduct a thorough analysis and determine whether it is 

representative of the performance of best-performing sources (the MACT floor) to require 

facilities in these source categories to achieve the same emission limitation during startup and 

shutdown as during normal operations, and that the default assumption be that such special 

provisions during startup and shutdown are needed. The commenter asked that the EPA provide 

a factual analysis supporting the EPA’s new conclusion that MACT standards can be achieved as 

well during all startup and shutdown periods.

The commenter expressed skepticism about whether the EPA conducted a sufficient analysis to 

demonstrate the achievability of the MACT emission limits established for normal operations 

during startup and shutdown events, because of likely limitations in the available data. The 

commenter stated that because of the difficulties in collecting reliable data during startup and 

shutdown periods, the EPA may have understated startup and shutdown emissions.

The commenter noted that it can be unclear whether a condition that leads to excess emissions 

should be characterized as a startup or shutdown event or a malfunction event, and the EPA may 

be analyzing data sets that exclude events that were treated as malfunctions but should be 

included in calculating average performance as startup or shutdown conditions.

Response: The commenters suggested that the EPA did not adequately analyze the ability of 

affected sources to meet Subpart RRR MACT emissions limits during startup and shutdown, but

the EPA did provide an explanation of the basis for its approach in the 2012 proposal, including 

the EPA’s conclusion that emissions during startup and shutdown will be low, and the 

commenters did not submit specific information to indicate that different standards are justified 

or to explain specifically why subpart RRR MACT standards are overly stringent during startup 

or shutdown. This failure to provide specific information to support their claims of 

unachievability is especially notable because the Subpart RRR MACT standards have already

applied at all times, including periods of startup and shutdown, since the SSM exemptions 

incorporated into Subpart RRR were vacated in the Sierra Club decision. The EPA disagrees 
66

with the suggestion that there is a “default assumption” that “special provisions during startup 

and shutdown are needed”. The commenters also do not identify or justify any specific different 

standards that should apply during startup and shutdown.

For secondary aluminum production processes where the MACT standards are expressed in units 

of pounds per ton of feed or similar units (i.e., thermal chip dryers, scrap dryer/delacquering kiln/ 

decoating kilns, dross-only furnaces, inline fluxers using reactive flux and group 1 furnaces), the 

2012 proposal included (and this final rule includes) an alternative method for demonstrating 

compliance with those limits based on emissions measured during startup and shutdown. In 

response to the commenters’ concern that the absence of feed/charge during startup and 

shutdown will result in a zero production and create mathematical problems when calculating 

production-based emissions, the final rule specifies that the feed/charge rate used in the 

calculation come from the most recent performance test associated with a production rate greater 

than zero, or the rated capacity of the affected source if no prior performance test data are 

available.

In response to comments on the 2012 proposal and because conducting meaningful emissions 

testing during periods of startup and shutdown can be problematic, we proposed in the 2014 

supplemental proposal (and are finalizing in this rule) an additional alternative method for 

demonstrating compliance with production-based subpart RRR emission limits during periods of 

startup and shutdown. As we explained in the 2014 supplemental proposal, these alternative 

compliance provisions reflect the MACT requirement for these periods. Specifically, compliance 

with production-based emission standards during startup and shutdown can be demonstrated by 

keeping records that show that the feed/charge rate was zero, the flux rate was zero and the 

affected source or emission unit either was heated with electricity, propane or natural gas as the 

sole sources of heat or was not heated. This alternative compliance method was based on the 

recognition that the source of HAP emissions is the processing of scrap and the use of fluxes 

during processing and that the heat for processing in this source category is generated 

exclusively by use of clean fuels—natural gas, propane or electricity. The following records 

must be kept for sources that use this alternative method of compliance: the date and time of 

each startup and shutdown, the quantity of feed/charge and flux introduced during each startup 

and shutdown and the types of fuel used to heat the unit during startup and shutdown.

Section 112(h) allows the EPA to set work-practice standards when “the application of 

measurement methodology to a particular class of sources is not practicable due to technological 

and economic limitations.” Section 112(h) “allows the EPA to substitute work practice standards 

for emission floors only if measuring emission levels is technologically or economically

infeasible.” Sierra Club v. EPA, 479 F. 2d 875, 880 (D.C. Cir. 2007). We specifically sought 

comment in the 2012 proposal on whether work practices should be applied for processes subject 

to production-based limits (i.e., standards expressed in units of pounds per ton of feed or similar 

units). We asked any commenters who supported the application of work practices to explain 

how the requirements of CAA section 112(h)(2) are met and to identify work practices that 

would be effective in limiting HAP emissions during periods of startup and shutdown for such 

processes. We did not receive and do not have information, from commenters or otherwise,

concerning the impracticability of applying measurement methodology that would be necessary

to prescribe work practice standards for periods of startup and shutdown in lieu of numerical 

emission standards contained in Subpart RRR.
67

We have reviewed the information available to us regarding startup and shutdown periods. Prior 

to the 2012 proposal we conducted an industry survey for emissions data including a request for 

information on emissions during startup and shutdown, but no such information on startup and 

shutdown emissions was received. A commenter notes the limited data available to the EPA, but 

neither this nor any other commenter submitted additional data on startup and shutdown 

emissions. Because scrap and reactive fluxing are the source of HAP emissions, we believe that 

startup and shutdown emissions will be very low and are not likely to cause a violation of the 

standards. We found no evidence that suggests that emissions are higher during startup or 

shutdown that might indicate a need for a different standard for these periods. The commenters 

have not provided any information to support a conclusion that sources cannot comply with the 

standards as proposed, and have not provided information to support development of different 

standards for startup and shutdown periods. Contrary to a commenter’s argument, we believe 

that the Subpart RRR MACT standards provide “continuous section 112-compliant standards”.

As we stated in the 2012 and 2014 proposals, the scrap processed and reactive fluxing used at 

secondary aluminum production facilities is the source of emissions. For that reason, we 

continue to expect that emissions during startup and shutdown will be no higher and probably

much lower than emissions during normal operations since no scrap will be processed, even if, as 

the commenter suggests, control equipment is operating at less than optimal efficiency. We know 

of no reason why facilities should not be able to comply during periods of startup and shutdown. 

We recognize that there is no charging during startup and shutdown periods. For that reason we 

proposed and are finalizing two alternative methods for demonstrating compliance with 

production-based emission limits during periods of startup and shutdown.

Thus, we set standards based on available information as directed by section 112. The Subpart 

RRR standards that apply during normal operation will also apply during startup and shutdown.

In response to comments received, we proposed in the 2014 supplemental proposal and are 

finalizing, with some revisions, definitions of startup and shutdown. See Comment #3 below.

Finally, as in 40 CFR 63.7(e)(1), we are requiring in 40 CFR 63.1511(b)that performance tests 

conducted under this subpart not be conducted during malfunctions because conditions during 

malfunctions are often not representative of normal operating conditions. The EPA is adding 

language in 40 CFR 63.1517(b)(19) that requires the owner or operator to record the process 

information that is necessary to document operating conditions during the test and include in 

such record an explanation to support that such conditions are representative of startup and 

shutdown operations.

Comment #3: One commenter (0197) stated that startup and shutdown periods are not defined in 

the rule, but rather only in the preamble to the proposed rule. The commenter supported the 

EPA’s definitions of startup and shutdown periods but, to reduce uncertainty, urged the EPA to 

include these definitions in the rule.

In a comment on the supplemental proposal, commenter 0288 stated that the definition of 

"startup" and "shutdown" were problematic as applied to reverberatory furnaces. The commenter 

stated that the proposed definition of "shutdown" appears to require that a group 1 reverberatory

furnace be tapped empty before shutdown can be said to have begun. The commenter stated that 
68

the implication is that emissions testing should include tapping the furnace until empty.

According to the commenter, group 1 reverberatory sidewell furnaces cannot be tested under this 

definition, which would require the furnace cycle to include a complete drain and refilling. The 

commenter stated that filling a reverberatory furnace from an empty condition can take 12 hours 

or more depending on furnace size and design. According to the commenter, this is not a 

representative (normal) condition when operating a reverberatory sidewell furnaces, which 

operates with a heel of molten metal at all times during normal operation. The commenter stated 

that a common practice when starting a reverberatory sidewell furnace from an empty condition 

is to use clean charge and no reactive flux until the molten heel is raised above the arch between 

the sidewell and main hearth; once this arch is covered, normal charging and fluxing practices 

can begin. 

The commenter stated that a group 1 rotary furnace can be tested beginning empty and finishing 

empty. Although this does not represent every furnace cycle it does represent one of the normal 

operating modes for this furnace type. The commenter suggested that, to accommodate normal 

operating procedures for both reverberatory and rotary group 1 furnaces, the definition of 

"shutdown" be revised to the following: 

"...that begins when the introduction of feed/charge is halted with the intention of 

removing all product and the intention of allowing the equipment to reach ambient 

temperature."

In a comment on the supplemental proposal on the definition of "startup," commenter 0288 

referred the EPA to their comment on the definition of "shutdown," and added that a 

reverberatory sidewell furnace, from a cold start, must be heated to normal operating 

temperatures while feed/charge is added. The commenter stated that this feed/charge normally is 

made up of clean charge and no reactive flux and once the furnace heel is at normal operating 

levels (above the arch), normal charging can proceed. The commenter suggested the definition of 

"startup" be revised to the following:

"... Startup ends at the point that feed/charge other than clean charge is introduced."

Commenter 0288 stated that the startup record required in paragraph 63.1517(b)(18) should 

include either identifying all materials charged to the furnace during startup or certification that 

only clean charge and no reactive flux was used until the arch between the sidewell and main 

hearth was covered. The commenter recommended that 63.1517(b)(18) be revised to the 

following:

"For each period of startup or shutdown for which the owner or operator chooses to 

demonstrate compliance for an affected source based on a feed/charge rate, other than 

clean charge, of zero, a flux rate of zero, ..."

Commenter 0288 stated that for the same reasons, the type of charge along with quantity should 

be recorded. The commenter suggested that paragraph 63.1517(b)(18)(ii) be revised to the 

following:

The type and quantity of feed/charge and quantity of flux introduced during each startup and 

shutdown, and ...”
69

In a comment on the supplemental proposal with regard to the definition of “shutdown,” 

commenter 0289 requested a clarification with how the definition relates to rotary tilt-type 

reverberatory furnaces, which operate on a batch-cycle. The commenter stated that, as proposed, 

the definition would classify the period between batches of this type of furnace, however brief 

and regularly scheduled, as a shutdown. The commenter stated that because this has implications 

for secondary aluminum processing units (SAPUs), and how emissions from members of a 

SAPU are counted, clarification as to whether the time between batches is a shutdown is 

appropriate.

In a comment on the supplemental proposal, commenter 0290 stated that they disagree with the 

proposed definition of shutdown in the supplemental proposal as it does not describe a furnace 

shutdown. The commenter stated that when a furnace is shutdown it is taken to a cold condition. 

The commenter stated that many melting and holding furnaces are operated batch-wise and 

between batches the furnace is still in operation and temperature is being maintained; the furnace 

is in a stand-by condition until the next batch is started. The commenter stated that the definition 

as proposed would apply between every batch and trigger burdensome record keeping 

requirements without any additional environmental benefit.

In a comment on the supplemental proposal, commenter 0294 stated that the typical operation of 

emission units within this source category are, for the most part, batch operations, i.e., 

feed/charge is introduced, feed/charge is halted, feed/charge previously fed into the emission unit 

is processed, and all of that feed/charge is subsequently removed from the emission unit; then 

another batch is begun and the cycle repeats itself. The commenter stated that as proposed, an 

affected facility would be shutting down numerous times daily as part of its normal batch 

operating mode; the commenter does not believe it was the EPA’s intent to include in the 

definition of shutdown these periods of normal operations or to create unnecessary

recordkeeping and reporting burdens for owners and operators. The commenter stated that they

agree that the halting of feed/charge and the removal of product from the emission unit are 

aspects of a shutdown; however, there are other key aspects of a shutdown that must be 

incorporated into the definition; those aspects are the discontinuation of heat input and the 

reduction of the functional temperature of the emission unit. The commenter recommended that

the EPA redefine “shutdown” to mean

"...the period of operation that begins when the introduction of feed/charge is 

intentionally halted, all product has been removed from the emission unit (e.g., by 

tapping a furnace), the source of heat is removed from the emissions unit, and a shutdown 

concludes when the emission unit has cooled to near ambient temperatures."

In a comment on the supplemental proposal, commenter 0295 stated that the proposed definition 

of a furnace shutdown in not accurate in that it would consider furnaces to be ‘shutdown’ in 

situations when they are in stand-by mode in between processing batches of metal with the 

furnace still in operation, the temperature maintained at or near normal operating levels, and any 

applicable air pollution control equipment operating. The commenter recommended that the 

definition be revised to indicate that ‘shutdown’ is a situation where the furnace temperature is 

brought to ambient after the metal charge has been removed to the greatest extent practicable as 

follows:
70

“Shutdown means the period of operation ... that begins when the introduction of 

feed/charge is halted, the heat sources have been turned off, and all product has been 

removed from the emission unit to the greatest extent practicable (e.g., by tapping a 

furnace). Shutdown and ends when the emission unit is at or near ambient temperature.”

In a comment on the supplemental proposal, commenter 0290 stated that the EPA correctly 

recognizes in the definition of startup that a shutdown furnace is in a cold condition by including 

the phase “warming from a cold start or a complete shutdown”. The commenter recommended 

that the EPA add the phrase “the burners are turned off and the furnace is being taken to a cold 

state” to the proposed definition of "shutdown."

In a comment on the supplemental proposal, commenter 0289 stated that in the proposed 

definition of “startup,” startup "begins with equipment warming up from a cold start or a 

complete shutdown." The commenter stated that there is no explanation for what constitutes a 

"complete" shutdown as opposed to the proposed definition of "shutdown" or how it differs from 

a "cold start." The commenter requested a clarification to forestall interpretation issues.

In a comment on the supplemental proposal, commenter 0295 stated that they have concerns 

with the definition of ‘startup’ and recommended that the definition of startup be revised as 

follows:

“Startup means the period of operation ... that begins with equipment warming from at or 

near ambient temperature. Startup ends at the point that flux or feed/charge is 

introduced.”

Response: In response to comments on the 2012 proposal, the EPA included definitions of 

startup and shutdown in regulatory text for the 2014 supplemental proposal. We reviewed the 

comments on the supplemental proposal including those expressing concerns over the proposed

definitions of "startup" and "shutdown," and the final rule addresses those concerns. In particular 

we revised the definitions to account for the fact that many furnaces are batch operations and are 

often in a standby condition that, under the proposed definitions, might have been considered to 

be shutdown. Also, we agree that the definition of "shutdown" should recognize that the 

beginning of shutdown includes halting of feed/charge, turning off the heat sources, and removal 

of product to the greatest extent practicable, and shutdown ends with cooling of the equipment to 

near ambient temperature. By modifying the definition of shutdown to begin after the removal of 

the heat source and to include cooling of the emission unit to near ambient temperature, the final 

rule distinguishes emission units that are shutting down from those that are in standby mode. The 

definition of startup also includes the introduction of flux as an end to startup. The final 

definition also recognizes that, after tapping, most furnaces (tilting furnaces are an exception) 

retain a molten metal heel and are not emptied completely. Regarding the definition of "startup," 

we disagree with commenter 0288's suggestion to revise the definition to state that startup ends 

with the addition of feed/charge "other than clean charge." The result of such a change would be 

that group 2 furnaces would never exit the startup mode. The commenter has not identified, nor 

do we envision any negative effects on sidewell furnaces if the definition of "startup" results in 

startup ending before the molten metal level reaches the top of the arch between the sidewell and 

the hearth. The final rule defines "shutdown" and "startup" for this source category as follows:
71

 Shutdown means the period of operation for thermal chip dryers, scrap 

dryers/delacquering kilns, decoating kilns, dross-only furnaces, group 1 furnaces, in-line 

fluxers, sweat furnaces and group 2 furnaces that begins when the introduction of 

feed/charge is intentionally halted, the source of heat to the emissions unit is turned off, 

and product has been removed from the emission unit to the greatest extent practicable 

(e.g., by tapping a furnace). Shutdown ends when the emission unit is near ambient 

temperature.

 Startup means the period of operation for thermal chip dryers, scrap dryers/delacquering 

kilns, decoating kilns, dross-only furnaces, group 1 furnaces, in-line fluxers, sweat 

furnaces and group 2 furnaces that begins with equipment warming from a shutdown, that 

is, the equipment is at or near ambient temperature. Startup ends at the point that flux or 

feed/charge is introduced.

Comment #4: One commenter (0197) indicated that the startup and shutdown emission 

calculation provision is confusing, may result in over reporting of emissions, and should be 

revised. The commenter indicated that the procedure is not a calculation of emissions, but rather 

an emission rate, and that according to the EPA’s definition, there is no product (aluminum 

chips) in a unit during startup and shutdown periods and would therefore yield zero emissions.

The commenter indicated that, with the exception of scrap shredders, emissions from sources 

covered by this subpart during these periods can be concluded to include only the byproducts of 

combustion. The commenter stated that these emissions, particularly in the case of dioxins and 

furans, should be negligible and may be accurately estimated using AP-42 emission factors or an 

engineering evaluation. The commenter recommended that the EPA should clarify the wording 

of the emission calculation equation and also allow facilities the option to demonstrate 

compliance with the standards through the use of AP-42 emission factors or an engineering 

evaluation. The commenter remarked that the EPA should not finalize a rule that inappropriately 

assumes emissions during startup are based on worst case emissions calculated during a 

performance test.

Response: We have revised the startup and shutdown emission calculation provisions in section 

63.1513(f)(2) of the final rule to clarify how the owner or operator would be able to demonstrate 

compliance for those affected sources subject to an emissions limit expressed in units of pounds 

per ton of feed, or μg TEQ or ng TEQ per Mg of feed. As a further alternative to measuring 

emissions during startup and shutdown and dividing by the feed rate from the most recent 

performance test associated with a production rate greater than zero (or the rated capacity of the 

affected source if no prior performance test data is available), we are also allowing that records 

of feed or charge to the furnace may be used to demonstrate that the furnace is in compliance 

with the emissions limits during startup and shutdown. Because the source of HAP emissions is 

the feed or charge material and reactive flux material, emissions during startup and shutdown 

should be appreciably lower than the emissions limits. The EPA is, therefore, allowing sources to 

use recordkeeping to demonstrate compliance with the standards during startup and shutdown as 

an alternative to stack testing. The owner or operator would keep records showing that during 

startup and shutdown, the feed/charge rate was zero, the flux rate was zero and the affected 

source or emission unit was heated with electricity, propane or natural gas as the sole sources of 

heat or was not heated, although by definition, if feed or charge is introduced into the process, 
72

the affected source is not operating in a startup or shutdown mode and the requirements for 

normal operations would apply. 

Comment #5: In a comment on the supplemental proposal, Commenter 0294 stated that their 

standard safe work practices and standard operating procedures do not allow reactive flux or 

feed/charge materials to be added to furnaces, in-line flux boxes and other affected sources 

during a startup; for this reason, startup emissions are negligible and well below MACT emission 

limits. The commenter stated that documenting these work practices and procedures for every

startup is an unnecessary recordkeeping burden and provides no environmental benefit. The 

commenter stated that all of their affected sources use either natural gas or electricity for heat 

and keeping a record of the types of fuel used to heat the unit for every startup also adds no 

value. The commenter recommended that the EPA should allow these facilities the option to 

submit an annual compliance certification stating that no flux and or feed/charge material was 

added and no heat source other than electricity, propane or natural gas was used during startup of 

the affected source. The commenter stated that the proposed records at §63.1517(b)(18) make no 

sense for shutdowns because, by definition, a shutdown begins when heat is removed and the 

introduction of feed/charge is halted; so, if there was no “lack of heating” or the flux rate and 

charge rate were greater than “zero”, the source would not be in “shutdown” by definition. The 

commenter recommended that the proposed records at section 63.1517(b)(18) be deleted and 

replaced with a compliance provision in section 63.1516 (b)(2) that reads:

"For each affected source choosing to demonstrate startup compliance based on 

§63.1513(f)(1): During each startup, no reactive flux and no feed/charge material was 

added to the emission unit and electricity, propane or natural gas was used as the sole 

source of heat."

Response: We agree with the commenter that where a facility adheres to standard practices and 

procedures during startup and shutdown that exclude the addition of flux and feed/charge 

materials to emission units or the use of heat sources other than electricity, propane or natural 

gas, or is not heated, requiring the facility to document these practices for every startup and 

shutdown would be unnecessary and burdensome where there is an alternative method for 

documenting compliance during startup and shutdown. While we agree that documenting the 

work practices and procedures for startups/shutdowns under the conditions described can be 

reduced, we don’t agree that annually is sufficient and are requiring documentation every 6 

months. In the final rule, section 63.1517(b)(19) gives sources that choose to demonstrate 

compliance based on the startup and shutdown recordkeeping provisions of section 

63.1513(f)(1), the option of submitting a semiannual report in accordance with section 

63.1516(b)(2) of the final rule certifying that during startup and shutdown , no flux and no 

feed/charge were added to the emission unit, and electricity, propane or natural gas were used as 

the sole source of heat or the emission unit was not heated.

Comment #6: In a comment on the supplemental proposal, commenter 0298 stated that the 

proposed definitions that would delineate periods of startup and shutdown, during which 

alternative requirements would apply, as well as an alternative method for determining 

compliance are directionally consistent with portions of their comments on the 2012 proposal 

that urged the EPA to look more carefully at the Agency’s assumption that facilities could meet 
73

limits based on normal operations during startup and shutdown just because less raw materials 

and fuel would be used during those periods.

Response: The EPA acknowledges the commenter’s support of the rule requirements for 

demonstrating compliance during periods of startup and shutdown. See above for responses to 

specific comments on the definitions of startup and shutdown and alternative methods for 

demonstrating compliance with production-based emission limits during startup and shutdown.

Comment #7: One commenter (0195) stated that the EPA in the 2012 proposal has not justified 

adding proposed §63.1511(a) and eliminating reference to the NESHAPs General Provision on 

representative performance testing, §63.7(e)(1). The commenter asserted that the D.C. Circuit 

did not vacate the provision the EPA proposes to replace, §63.7(e)(1), in Sierra Club v. EPA, and 

according to the commenter, §63.7(e)(1) does not refer to or rely on provisions that were vacated 

in Sierra Club v. EPA. The commenter argued that the Sierra Club decision does not authorize

the EPA to (1) change existing MACT standards so that the EPA, in turn, could (2) direct a 

source to conduct performance testing during abnormal operations, such as startups, shutdowns 

or malfunctions.

The commenter argued that requiring sources now to demonstrate compliance with numerical 

emission limitations in the existing MACT standards, using performance tests or continuous 

monitoring, even while the source is in startup or shutdown mode or is experiencing a 

malfunction, definitely has the effect of making those existing MACT standards more stringent. 

The commenter asserted that the EPA cannot simply “amend” existing MACT standards in a 

way that can make those standards more stringent without (a) providing an adequate justification 

for departing from the EPA’s previous judgment about the appropriate level of the standards and 

the appropriate conditions for performance testing and (b) demonstrating that the revised 

standards would still meet the criteria of CAA section 112(d). The EPA’s total failure to do so 

renders the Proposed Rule inadequate notice for public comment. If the EPA wishes to change 

the performance tests applicable to the existing MACT standards, making them more stringent, 

then it must at a minimum withdraw and re-propose the requirements, with adequate explanation 

and justification.

Response: As noted by the commenter, in addition to our ministerial action removing the 

vacated SSM exemption from emission standards (codified in General Provisions sections 

63.6(f)(1) and (h)(1), formerly made applicable to this source category in Appendix A to Subpart 

RRR, and vacated by the Sierra Club decision), we also made inapplicable to this source 

category the SSM exemption from performance testing (see General Provisions section 

63.7(e)(1)).7The categorical exemption from performance testing for periods of SSM made 

 

7

Section 63.7(e)(1) provides: “Site-specific test plan. Prior to conducting any performance test required by this 

subpart, the owner or operator must prepare a site-specific test plan which satisfies all of the rule requirements, and 

must obtain approval of the plan pursuant to the procedures set forth in § 63.7(c). Performance tests shall be 

conducted under such conditions as the Administrator specifies to the owner or operator based on representative 

performance (i.e., performance based on normal operating conditions) of the affected source. Operations during 

periods of startup, shutdown, and malfunction shall not constitute representative conditions for the purpose of a 

performance test, nor shall emissions in excess of the level of the relevant standard during periods of startup, 

shutdown, and malfunction be considered a violation of the relevant standard unless otherwise specified in the 

relevant standard or a determination of noncompliance is made under §63.6(e). Upon request, the owner or operator 
74

sense when SSM periods were exempt from emission standards. Such an exemption is no longer 

appropriate because emission standards now apply at all times for this source category. Instead, 

the final rule provides in section 63.1511(a) that “[p]erformance tests shall be conducted under 

such conditions as the Administrator specifies to the owner or operator based on representative 

performance of the affected source for the period being tested.”8In addition, the final rule 

provides that performance tests should not be conducted during malfunctions. See section 

63.1511(b). 

The removal of the exemption from performance testing for periods of startup and shutdown 

does not affect the stringency of the underlining emission standards nor does it alter the basic 

requirement that performance tests be conducted under conditions based on representative 

conditions. We note that subpart RRR requires initial performance tests in section 63.1511(b) 

and periodic performance tests every 5 years for major sources in section 63.1511(e), but these 

provisions do not necessarily require that performance tests be conducted during startup and 

shutdown periods, although the EPA maintains authority under Subpart RRR and the Clean Air 

Act to require such testing as appropriate. Sections 63.1511 and 63.1512 specify conditions and 

procedures for performance testing for this source category, some of which have been revised in 

this rulemaking as discussed in the preambles to the proposed and final rules, and elsewhere in 

the response to comments. In addition, we are finalizing two alternative methods for 

demonstrating compliance with production-based emission limits during periods of startup and 

shutdown, including one alternative method that relies on recordkeeping and not on performance 

testing. We note that the latter alternative method was proposed in the 2014 supplemental 

proposal, subsequent to Commenter 0195’s comments on the 2012 proposal.

5.3 Malfunction and Affirmative Defense

Comment #1: A commenter (0190) recommended that the EPA modify the affirmative defense 

provisions so that it is a “rebuttable presumption.” The commenter was concerned that allowing 

a facility to interpose an affirmative defense for violations caused by malfunctions implies that 

the facility is guilty until proven innocent and improperly shifts the burden to the facility. 

Therefore, the commenter suggested that the EPA establish a rebuttable presumption (rather than 

affirmative defense) where it is presumed that any violation occurring during the malfunction 

was not the facility’s fault unless the Agency proves certain facts that are enumerated in the 

rules. This will allow the Agency to challenge the alleged deviation without compromising the 

legal rights of either party.

While commenter 0190 would prefer the EPA use a rebuttable presumption, should the Agency

keep the affirmative defense concept, the commenter suggested the following modifications to 

the language to make it more usable. The commenter suggested the EPA should drop the 

reference to “any” activity. There were also several references to “All” that would make it 

difficult to satisfy the requirements of an affirmative defense. In addition, the language in the 

provision was contradictory. In paragraph (a), the phrase “preponderance of evidence” was used 

 

shall make available to the Administrator such records as may be necessary to determine the conditions of 

performance tests.”

8 As noted above, section 63.1511(a) also provides, unchanged by this rulemaking, for the owner or operator to 

prepare a site-specific test plan and obtain approval pursuant to section 63.7(c).
75

while later in that paragraph (iii), the language referred to “any activity” meaning that more than 

preponderance of evidence was needed. This same trend occurred in paragraphs (5) – “All 

possible,” (6) “All,” (7) “All of the actions,” and (8) “At all times.” While “all” would include 

“preponderance,” “preponderance” does not mean all of the time. The commenter suggested that 

the phrase “preponderance of evidence” is adequate and the references to “all” and “any” in the 

later paragraphs should be modified.

Commenter 0190 believed that a formal “root cause analysis” (as the term is understood by many

engineers) should only be used when other reasonable methods fail to show what caused the 

malfunction or when the serious nature of an event might make such an analysis necessary.

Moreover, other tools may be more appropriate (e.g., failure mode and effect, fault tree, etc.) or 

more powerful tools may be introduced in the future. The facility is the only one that can and 

should decide what tool to use to determine the cause of the malfunction. The commenter noted 

that to some companies and local regulators, the term “root cause analysis” implies a specific 

formal process. The commenter indicated that there are several techniques that may be called 

“root cause analysis,” depending on the author and industry. If the EPA intended for the facility

to investigate and fix the source of the malfunction so that it is less likely to recur, the 

commenter supported that concept but suggested that the Agency use an alternative term that 

does not carry a specific meaning. However, if the Agency envisioned a formal process for 

determining the root cause for every malfunction, no matter how simple, the commenter believed 

that this is unnecessary and would result in excess efforts with no environmental gains.

The commenter also noted that it is impossible to eliminate the causes for certain malfunctions 

(e.g., lightning strikes).

One commenter (0190) also noted that the EPA does not allow facilities to assert an affirmative 

defense for the exceedance of an emission limit during malfunctions if the EPA is seeking to 

enforce that emission limit through injunctive relief. The commenter stated that the Agency took 

that position based on a memorandum, State Implementation Plans: Policy Regarding Excessive 

Emissions During Malfunctions, Startup, and Shutdown at 2 (Sept. 20, 1999) (SIP SSM Memo). 

The commenter asserted that this policy is wrong and that the type of legal action or relief should 

have no bearing on the availability of this defense. The commenter concluded that the type of 

legal action the EPA uses to enforce a violation of its emission limits is simply irrelevant to 

whether the violation should be excused because of circumstances beyond the facilities control.

The commenter (0190) continued that not allowing an affirmative defense in an action for 

injunctive relief is arbitrary and capricious. As the D.C. Circuit Court stated in Essex Chem. 

Corp. v. Ruckelshaus, 486 F.2d 427. 433 (D.C. Cir. 1973) a case reviewing a § 111 rule, the 

court held that startup, shutdown, or malfunction (“SSM”) provisions are “necessary to preserve 

the reasonableness of the standards as a whole.” The D.C. Circuit Court of Appeals has also 

noted that “[a] technology-based standard discards its fundamental premise when it ignores the 

limits inherent in the technology.” NRDC v. EPA, 859 F.2d 156, 208 (D.C. Cir. 1988). 

Therefore, the commenter indicated that the EPA should not apply a policy drafted to “ensure 

that SIPs provide for attainment and maintenance of the national ambient air quality standards 

(“NAAQS”) and protection of prevention of significant deterioration (PSD) increments” and 

other risk-based programs, SIP SSM Memo at 2, to the CAA § 129 technology-based program.
76

Commenters (0190, 0193, 0194) suggested that the EPA clarify affirmative defense provisions 

by modifying the regulatory language in § 63.11501(e) to address the commenters’ concerns and 

to make an affirmative defense a more useful tool (using strikeout to show text deleted and 

underline to show text added): 

§ 63.1520 Affirmative defense for violation of emission limit during malfunction.

In response to an action to enforce the standards set forth in this subpart, you may assert 

an affirmative defense to a claim for civil penalties for violations of such standards that 

are caused by malfunction, as defined at § 63.2. Appropriate penalties may be assessed, 

however, if you fail to meet your burden of proving all of the requirements in the 

affirmative defense. The affirmative defense shall not be available for claims for 

injunctive relief.

(a) To establish the affirmative defense in any action to enforce such a limit, you must 

timely meet the notification requirements in paragraph (b) of this section, and must prove 

by a preponderance of evidence that`:

(1) The excess emissions:

(i) Were caused by a sudden, infrequent and unavoidable not reasonably preventable 

failure of air pollution control and monitoring equipment, process equipment, or a 

process to operate in a normal or usual manner; and

(ii) Could not have been reasonably prevented through careful planning, proper design or 

better operation and maintenance practices; and

(iii) Did not stem from any activity or event that could have been reasonably foreseen and 

avoided, or planned for.

(iv) Were not part of a recurring pattern indicative of inadequate design, operation, or 

maintenance; and

(2) Repairs were made as expeditiously as possible when the applicable emission 

limitations were being exceeded. Off-shift and overtime labor were used, to the extent 

practicable to make these repairs; and

(3) The frequency, amount and duration of the excess emissions (including any bypass) 

were minimized to the maximum extent practicable during periods of such emissions; and

(4) If the excess emissions resulted from a bypass of control equipment or a process, then 

the bypass was unavoidable to prevent loss of life, personal injury, or severe property 

damage; and

(5) All possible Reasonable steps were taken to minimize the impact of the excess 

emissions on ambient air quality, the environment and human health; and
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(6) All emissions monitoring and control systems were kept in operation if at all possible, 

consistent with safety and good air pollution control practices; and

(7) All of the actions in response to the excess emissions were documented by properly 

signed, contemporaneous operating logs; and

(8) At all times, the affected source was operated in a manner consistent with good 

practices for minimizing emissions; and

(9) A written root cause analysis report has been prepared, the purpose of which is to 

determine, correct, and eliminate mitigate the primary causes of the malfunction and the 

excess emissions resulting from the malfunction event at issue. Facility personnel will 

determine the appropriate type of analysis required (may include but not limited to root 

cause analysis, failure mode and effect, fault tree, etc.) to identify the cause of the 

malfunction. The analysis report shall also specify, using best monitoring methods and 

engineering judgment, the amount of excess emissions that were the result of the 

malfunction.

(b) Reports. The owner or operator seeking to assert an affirmative defense shall submit a 

written report to the Administrator within 45 days of the initial occurrence of the 

violation of the standards in this subpart, which may be the end of any applicable 

averaging period, to demonstrate, with all necessary supporting documentation, that it has 

met the requirements set forth in paragraph (a) of this section. The owner or operator may

seek an extension of this deadline for up to 30 additional days by submitting a written 

request to the Administrator before the expiration of the 45 day period. Until a request for 

an extension has been approved by the Administrator, the owner or operator is subject to 

the requirement to submit such report within 45 days of the initial occurrence of the 

violation. A written report to demonstrate, with all necessary supporting documentation, 

that you have met the requirements set forth in paragraph (a) of this section. This report 

should be submitted as a part of the excess emissions and continuous monitoring system 

performance report and summary report as required in § 63.10(e)(3).

One commenter (0194) stated that the proposed affirmative defense language for periods of 

malfunction needs clarification and revision to make it usable. The commenter asserted that the 

proposed affirmative defense language is similarly made unusable by numerous limitations such 

as “could not have been prevented”, “could have been foreseen and avoided”, “all possible 

steps”, “at all times” and “all actions ...documented”. The commenter stated that this language 

so narrowly limits the affirmative defense that the provisions would have no practical application

and provide no real legal defense for owners and operators, who are the intended users.

One commenter (0190) reported that the language the EPA is proposing in § 63.1520 is similar 

to the definition in § 63.2 with one major exception. In the proposed language, one of the 

conditions for an affirmative defense is that the excessive emissions were caused by a “sudden, 

infrequent, and unavoidable failure...” The General Provisions definition of malfunction uses the 

phrase “not reasonably preventable” instead of the word “unavoidable.” The EPA obviously

understands this difference in that they quote § 63.2 on page 8,599 of the preamble yet still 

makes a change in definition of malfunctions in § 63.1520. The commenter believed that it is 
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inappropriate have two different definitions of malfunction and requested that the Agency revise 

the language to reflect the General Provisions definition of a malfunction.

One commenter (0191) commended the agency for adding an affirmative defense to civil 

penalties for violations of emission limits caused by malfunctions but recommended that the 

facilities asserting the affirmative defense be allowed sufficient latitude to demonstrate that the 

emission non-compliance was in fact caused by a sudden, infrequent, and unavoidable failure of 

air pollution control and monitoring equipment, that repairs were made as expeditiously as 

possible when the applicable emission limitations were being exceeded, and that effective steps 

were taken to minimize the impact of the excess emissions on ambient air quality, the 

environment and human health.

One commenter (0195) recommended that in proposed section 63.1520(a)(6), the phrase “if at all 

possible” should not be used because it is an extreme term that bears no relation to good air 

pollution control practices. The commenter suggested that this provision be qualified, as the EPA 

has qualified similar provisions in the NESHAP General Provisions in 40 C.F.R. §63.6 with 

caveats that the operation must be consistent with safety and good air pollution control practices, 

that the provision does not require the source to make further efforts to reduce emissions below 

what the standards require, and that it does not require regular operation of backup or standby 

pollution control equipment.

The commenter stated that the EPA cannot adopt the kind of absolute requirements implied by

the Proposed Rule, without an explanation of why it is necessary and appropriate to do so. The 

commenter cited several recent NESHAP that inserted language clarifying that the general duty

to minimize emissions “does not require the owner or operator to make any further efforts to 

reduce emissions if levels required by this standard have been achieved.” See 76 Fed. Reg. 

22,566, 22,583, col. 3 (April 21, 2011).

One commenter (0195) recommended that the language of proposed section 63.1520(a)(4) may

be difficult or impossible for a source to demonstrate. The commenter stated that there could be 

substantial room for disagreement about what constitutes an appropriate exercise of air pollution 

control practice. The commenter maintained that there is nothing inherent to standards under 

CAA section 112 that requires a source to avoid bypassing control equipment to such a degree, 

nor has the EPA attempted to explain, why the CAA would disfavor bypassing “a process” in 

this way.

One commenter (0195) stated that the language in proposed section 63.1520(a)(5) regarding “all 

possible steps” is subjective, and presents a disconnect between the absolute and extreme 

requirement of the affirmative defense and the provisions of the CAA designed to attain national 

ambient air quality standards and protect human health and the environment. The commenter 

observed that the CAA does not require sources to take “all possible steps” to control emissions, 

even with respect to the residual risk of hazardous air pollutant emissions addressed under CAA 

section 112(f). The commenter claimed it is unclear how this criterion for qualifying for the 

affirmative defense differs from proposed section 63.1520(a)(3), which requires that the 

frequency, amount, and duration of excess emissions “were minimized to the maximum extent 

practicable.” The commenter stated that unless the EPA explains what additional showing would 

be needed by section 63.1520(a)(5), that paragraph should be eliminated.
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One commenter (0197) indicated that an affirmative defense is insufficient to absolve the EPA of 

its duty to set Section 112-compliant standards. The commenter stated that rather than attempt to 

promulgate section 112-compliant standards, the EPA proposes to establish an “affirmative 

defense” for malfunctions only. The commenter declared this “affirmative defense” to be 

insufficient to meet the EPA’s obligations under section 112. The commenter also noted that the 

EPA has previously found a case-by-case basis consideration of potential enforcement to be a 

less desirable route to address malfunctions. 

One commenter (0195) stated that the proposed affirmative defense is not a substitute for 

addressing malfunction events in the emission standards as emission limitations achieved by 

best-performing existing sources under CAA section 112(d)(3), or as beyond-the-floor emission 

standards under CAA section 112(d)(2). 

The commenter questioned the EPA’s legal authority in the CAA to shift the burden to the 

regulated community of proving (or disproving) essential elements of an alleged violation. The 

commenter asserted that if the EPA adopts an approach along the lines of the proposed 

affirmative defense, it should be stated instead in terms that, once a source has claimed that its 

excess emissions were related to a malfunction, it will not be considered to have violated the 

standards unless the enforcement authority demonstrates that the source is not entitled to claim 

the malfunction.

One commenter (0195) stated that the EPA should provide the same kind of affirmative defense 

that it proposes for malfunctions for startup and shutdown events as well.

One commenter (0197) asserted that, while the EPA has authority to establish an affirmative 

defense for SSM events, the criteria outlined in the proposed rule are arbitrary and capricious and 

should be revised. The commenter noted that the Proposed Rule would limit the affirmative 

defense to malfunctions only and not include startup and shutdown periods. The commenter 

discussed some legal precedent supporting the EPA’s authority to provide an affirmative defense 

for malfunctions. However, the commenter believed that the proposed affirmative defense 

includes criteria that are unduly restrictive so as to not constitute a defense at all.

One commenter (0195) stated that is not clear what the affirmative defense covers. The 

commenter asked if the term “civil penalties,” which is not defined in the Proposed Rule, could 

possibly be intended to apply to a “civil administrative penalty” imposed by the EPA under CAA 

section 113(d), noting that the term “civil penalty” in other contexts means only penalties 

imposed by a court. The commenter asked if the affirmative defense applies to “noncompliance 

penalties” under CAA section 120 (which apply, inter alia, to noncompliance with a section 112 

NESHAP). The commenter asserted that to meet the purported purpose of the affirmative 

defense, which is to provide relief from emission limitations that cannot be met at times even 

with equipment that is properly designed and maintained the affirmative defense would need to 

apply to civil and administrative penalties, including noncompliance penalties. The commenter 

noted that in the proposed rule's preamble, the EPA states that, if a source cannot prove its 

entitlement to the affirmative defense, appropriate penalties could be assessed in accordance with 

section 113 of the CAA. The commenter stated that this does not answer the questions presented 

in this paragraph.
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The commenter stated that it is unclear as well how the affirmative defense would apply to 

enforcement actions by state and local governments, or to private citizen enforcement actions 

under CAA section 304. The commenter maintained that an affirmative defense should clearly

state that it is applicable to enforcement actions by states or citizen-suit plaintiffs, as well.

The commenter observed that the EPA did not give any explanation for why the affirmative 

defense would not apply to injunctive relief. The commenter stated that if the excess emissions 

associated with the equipment or process failure really are not reasonably preventable, then there 

is no apparent reason why an affirmative defense to a claim for injunctive relief should not also 

be available. The commenter argued that in fact, as a matter of law, injunctive relief may not be 

available in cases where a civil penalty cannot be imposed. See Sierra Club v. Otter Tail Power 

Co., 615 F.3d 1008 (8th Cir. 2010) (under concurrent remedy doctrine, injunctive relief for a 

CAA violation is barred when civil penalty is barred by statute of limitations). 

The commenter asserted that maintaining liability for injunctive relief renders the affirmative 

defense particularly ineffective with respect to citizen suits. The commenter postulated the if the 

source is even potentially subject to injunctive relief and, therefore, could be required to pay the 

citizen-plaintiff’s attorneys fees even if the source successfully demonstrated that it otherwise 

qualified for the affirmative defense, then the affirmative defense would not accomplish the 

EPA’s stated objective of providing relief in situations where the emission limitations cannot be 

met despite proper design and operation of process and control equipment.

The commenter stated that the EPA has not addressed these and other apparent limitations and 

shortcomings of the affirmative defense, which make it an entirely inadequate substitute for 

setting MACT standards that include provisions for SSM events.

The commenter stated that thus, at a minimum, the EPA should state that the affirmative defense 

applies to civil penalties, civil administrative penalties, noncompliance penalties, and injunctive 

relief, in an action brought by the EPA, a state, or a citizen-suit plaintiff. The commenter 

suggested that the EPA also should reword the affirmative defense, so that it states that a source 

“will not be deemed in violation of” the MACT standards for excess emissions or other 

deviations from the standards, associated with a startup, shutdown, or malfunction event, unless 

the event, and the source’s response to the event, do not meet the criteria spelled out in the 

regulations. The commenter stated that configured in this way, the provision for malfunction 

events should be called something other than an “affirmative defense,” such as an “alternative 

standard for SSM events.”

One commenter (0195) disagrees with the EPA's tying the proposed affirmative defense to a 

continuously applicable section 112-compliant emission standard as discussed in Sierra Club v. 

EPA. The commenter argued that if the CAA required that the EPA be able to enforce a 

numerical limitation on a source’s hazardous air pollutant emissions at all times, which the 

commenter disputes, then excluding injunctive relief from the affirmative defense, as the EPA 

proposes, would not meet that requirement. The commenter stated that injunctive relief is 

prospective only: it does nothing to prevent (or even penalize) a past excess emissions event, 

while under the approach the EPA proposes, a malfunction that causes emission limitations to be 

exceeded could trigger injunctive relief even where the affirmative defense prevented the EPA 

from imposing penalties, that injunctive relief would not address directly the past event (which, 
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by definition, was unexpected), but would only require the source to do something different in 

the future. 

The commenter asked, if the Agency’s providing for injunctive relief satisfies the CAA 

“requirement” for a continuously applicable section 112-compliant emission standard that the 

EPA posits, why is it necessary for the EPA to change the existing MACT standards to impose 

civil penalties for malfunctions (and then excuse a few of them with the affirmative defense), 

rather than simply providing that malfunction events, although they continue to be exempt from 

civil penalties, are not exempt from potential injunctive relief? The commenter stated that it 

would reduce if not eliminate the issues of reasonableness and Constitutional due process that the 

Proposed Rule presents when it imposes penalties for exceedances that the source could not 

reasonably have prevented.

One commenter (0195) stated that the affirmative defense as written is unreasonable and 

impracticable. The commenter asked that the affirmative defense must be substantially modified 

for it to provide any significant relief. The commenter suggested that the affirmative defense 

needs to state clearly that a source that qualifies for the affirmative defense shall not be deemed 

to have violated the applicable standards during that time. The commenter maintained that if the 

EPA does that, it may be unnecessary to state also that the affirmative defense relieves the source 

from liability for all types of penalties and injunctive relief (save criminal penalties), but that 

should be the clear effect of qualifying for the affirmative defense. The commenter 

recommended that the affirmative defense also should be available not only for malfunctions, but 

also for excess emissions during startup and shutdown.

The commenter discussed aspects of the affirmative defense that make it unavailable as a 

practical matter for many, if not most malfunctions. 

One commenter (0195) stated that several of the conditions for establishing an affirmative 

defense in proposed §63.1520(a) list numerous items which may be appropriate considerations in 

determining whether excess emissions during a malfunction should be considered a violation, but 

which ought not to be listed as mandatory criteria, all of which have to be met in order for a 

source even to raise an affirmative defense.

The commenter observed that a number of the conditions for establishing an affirmative defense 

use phrases that are subject to a wide range of interpretations, and that on their face do not 

recognize any need for reasonableness or cost effectiveness. The commenter suggested that in 

some cases, it may have been possible to prevent the malfunction, or to have further reduced the 

excess emissions, if the source had spent huge amounts of money or had imposed economically 

impracticable constraints on its operation. The commenter observed that affirmative defense, as 

proposed, leaves open the possibility that a source will be considered to be in violation because 

the enforcement authority decides subjectively that in one or more respects it would have been 

“proper” or “possible” for the source to take further steps to prevent or minimize the 

malfunction, allowing the EPA or the court to impose an extreme version of MACT during 

malfunction periods, without any application of the beyond-the-floor factors in CAA section 

112(d)(2). The commenter noted that the descriptors in the criteria for demonstrating the 

affirmative defense (section 63.1520(a)(1)(ii), section 63.1520(a)(1)(iv),section 63.1520(a)(2), 

section 63.1520(a)(5), and section 63.1520(a)(6)) would inevitably lead to varying conclusions 
82

as to whether a violation has occurred, resulting in inconsistency from one jurisdiction to the 

next.

One commenter (0195) asserted that the requirement in proposed section 63.1520(a)(9) that the 

source “have prepared a written root cause analysis to determine, correct and eliminate the 

primary causes of the malfunction and the excess emissions resulting from the malfunction event 

at issue” does not implement the statutory criteria for standard-setting under section 112. The 

commenter maintained that if read literally, it would mean that a source could never take 

advantage of the affirmative defense if the source was unable to determine the primary cause of 

the malfunction or was unable to correct that cause. 

One commenter (0195) stated that 90 days is the minimum amount of time to provide the kind of 

extensive documentation required by the affirmative defense as currently written, including a 

completed root cause analysis, unless the EPA streamlines the criteria for affirmative defense. 

The commenter disagreed that the starting time for the proposed 45-day period for submitting a 

written report should be on the date of “the initial occurrence of the exceedance of the 

standards.” The commenter observed that much of the required content of that written report 

could not be created until the malfunction event ceased, which could be many days after the 

malfunction commenced and a limit on the amount of time a source would have to prepare the 

report.

The commenter argued that the provision allowing an extension of the reporting deadline of up 

to 30 days would provide little practical relief as the source would have to submit the report 

within 45 days unless the EPA Administrator granted the extension request before the expiration 

of the initial 45-day period, which is not likely to happen until shortly before, if not after, the 

report would otherwise be due. The commenter recommended that the rule should provide that a 

request for extension of the reporting deadline on which the Agency has not acted within 10 days 

is considered granted.

The commenter requested that malfunction reporting be required on a semi-annual basis, for 

malfunctions that occurred during the preceding six months (the same frequency as similar 

reports pursuant to NESHAPs and Title V permit requirements). The commenter explained that 

this would enable the EPA to review the source’s compliance history and the measures being 

taken to address malfunctions, without imposing unworkable reporting deadlines on sources or 

potentially encouraging sources to submit numerous “protective” reports to the Agency for 

malfunctions that may not ultimately result in the source exceeding a 30-day average emission 

limitation.

One commenter (0195) claimed that the requirement in proposed section 63.1520(b) to submit a 

written report to the Administrator within 45 days of the initial occurrence of the malfunction 

that demonstrates, “with all necessary supporting documentation,” that the source met all of the 

multitude of criteria for the affirmative defense, is unreasonable and unnecessary. The 

commenter disagreed that a person could be determined to have acted unlawfully unless the 

person has submitted his or her entire defense before he or she is even notified of a potential 

enforcement action. The commenter asserted that the enforcement authority would be able to see, 

based on the kind of short malfunction or deviation report sources already submit under many air 
83

programs, that an exceedance of the Proposed Standards resulted from an unforeseen and 

unavoidable equipment failure or process upset. The commenter observed that it is extremely

inefficient and burdensome, for both sources and regulators alike, to require a complete 

justification of the affirmative defense before the enforcement authority has indicated any need 

for further investigation.

The commenter further noted that affirmative defense notifications would swamp the EPA and 

state agencies with unnecessary paperwork, and for no clear benefit, because sources will need to 

submit notifications of the malfunction, with all the supporting documentation, whenever a 

malfunction defense could be claimed

One commenter (0197) supported the incorporation of the definition of “malfunction” in 40 

C.F.R. §63.2 as a long-established definition that the regulated community is familiar with. The 

commenter noted, however, that the criteria outlined in the Proposed Rule to establish the 

affirmative defense are inconsistent with this definition and should be eliminated. The 

commenter declared that the criteria are substantially more restrictive than the requirements to 

show a malfunction under the definition, and these more restrictive criteria would result in only a 

subset of malfunctions being considered eligible for the affirmative defense, if any at all, 

undermining the purpose of the provision. The commenter noted that the criteria for establishing 

an affirmative defense may impose a greater burden on regulated entities than would otherwise 

be required by the standards; they are redundant of the general duty standard and may cause 

undue confusion as to the applicable requirements. The commenter stated that other criteria more 

stringent than, or at least redundant with, the general duty standard, should be eliminated. 

If the EPA subsequently determines to utilize an affirmative defense, then the commenter 

believed that the EPA should eliminate the criteria in the proposal, and require the regulated 

entity to establish that a malfunction, as defined in section 63.2 occurred. Alternatively, the 

commenter recommended that the EPA could use the Clean Water Act’s upset defense as a 

model, rather than the 1983 and 1999 EPA memoranda on excess emissions that do not 

adequately address the treatment of SSM events in technology-based standards.

One commenter (0190) stated that, in the recently signed National Emission Standards for 

Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers Production final rule (FR 

notice if available), the EPA incorporated the reporting requirements for an affirmative defense 

as a part of the excessive emissions reporting requirements of 63.10(e)(3). The commenter 

suggested that the Agency modify the reporting requirements in this rule to match the reporting 

requirements in 63.11895(b).

One commenter (0190) stated that as facilities and the EPA move toward electronic 

recordkeeping, it does not make sense to require keeping a “properly signed, contemporaneous 

operating logs” as a requirement for an affirmative defense. The commenter noted that there are 

a number of electronic methods for maintaining records currently available and suggested 

modifying this provision.

One commenter (0192) stated that EPA properly recognizes CAA section 112 does not require 

that emissions that occur during periods of malfunction be factored into development of CAA 

section 112 standards and objected to the proposed malfunction defense to the extent it includes 
84

a non-malfunction presumption. The commenter stated that creating a new program for 

malfunctions is not justified and conflicts with the straightforward definition under 40 CFR 

§63.2, and recommended that the proposed affirmative defense rule provision be dropped.

One commenter (0193) recommended the EPA establish a rebuttable presumption (rather than 

affirmative defense) where it is presumed that any violation occurring during the malfunction 

does not automatically result in civil liability and the imposition of civil monetary penalties 

unless the Agency proves certain facts that are enumerated in the rules.

One commenter (0195) asserted that being able to assert a defense is not the same as complying 

with emission limitations that are properly set in accordance with CAA section 112. The 

commenter expressed concern that despite the fact that a source believes it qualifies for the 

affirmative defense, it may be considered to have violated the standards—and may have to report 

violations, certify noncompliance, etc.—until there has been an enforcement proceeding and the 

source has successfully asserted the affirmative defense. The commenter stated that the 

affirmative defense places the source in the position of having to prove its innocence, rather than

the EPA or another enforcement authority having to prove that the source violated the CAA.

One commenter (0195) maintained that the EPA’s discussion of the regulatory burden of the 

affirmative defense indicates that the EPA does not believe the affirmative defense will mitigate 

to any significant extent the unreasonableness of imposing emission limitations that the Agency

recognizes sources will not be able to meet when malfunctions occur. According to the 

commenter, the EPA states that in only a small number instances would source operators use the 

affirmative defense – presumably, the commenter stated, because the criteria the EPA proposes 

for qualifying for the affirmative defense will, as discussed above, be difficult if not impossible 

to meet. The commenter asserted that the EPA believes that it has so cabined the affirmative 

defense that it will effectively be unavailable, meaning that it will provide virtually no relief to 

address the legal necessity that the EPA not impose emission limitations that sources will be 

unable to achieve despite the proper design and operation of their facilities. The commenter 

stated that it is not credible for the EPA to claim that, despite the wide variety of circumstances 

at individual facilities and the wide variation in the number of facilities covered by particular 

NESHAP source categories, there will only be 0-3 circumstances in each of those source 

categories (or groups of source categories) qualifying for the affirmative defense over a period of 

three years.

One commenter (0195) disagreed with the EPA’s estimate of the cost of the notification,

reporting, and recordkeeping requirements associated with a source asserting the affirmative 

defense for a malfunction. The commenter believed that this estimate is extremely low, given the 

approximately one dozen different demonstrations the source is required to make under the 

criteria proposed for the affirmative defense, and given that this estimate also presumably 

includes the cost of preparing the written root cause analysis, which must not only “determine, 

correct, and eliminate the primary causes of the malfunction and the excess emissions resulting 

from the malfunction” but also must “specify, using best monitoring methods and engineering 

judgment, the amount of excess emissions that were the result of the malfunction.”
85

The commenter stated that the burden estimate is arbitrary and irrational, noting a range of costs 

for the reporting and recordkeeping required to qualify for the affirmative defense for a single 

malfunction event for various recent NESHAP.

One commenter (0195) stated that the reasons the EPA estimates so few incidents will qualify

for the affirmative defense is that the Agency has defined “malfunctions” to be “infrequent” 

events that could not have been foreseen and has suggested that they cannot be “predictable and 

routine aspects of a source’s operations.” The commenter claimed that the EPA shows a bias that 

assumes sources currently operate with little concern for controlling excess emissions, because 

the sources can claim that those excess emissions are covered by the malfunction exemption in 

the current regulations. The commenter disagreed with this assumption. The commenter 

maintained that the SSM provisions in the existing Secondary Aluminum Production NESHAPs 

require the source to take measures to prevent or minimize excess emissions during SSM events 

to the extent practical and to follow a written SSM plan, and the source also is subject to a 

general duty under the NESHAPs General Provisions to operate and maintain the source “in a 

manner consistent with safety and good air pollution control practices for minimizing 

emissions.” The commenter urged the EPA to not base its rulemaking on an unsupported 

assumption that sources subject to the Proposed Rule are not operating in accordance with 

existing regulations.

The following comments were received on the supplemental proposal regarding the proposed 

change to the affirmative defense provisions:

Commenter 0298 stated that the supplemental notice implies that the affirmative defense was 

not a necessary part of the standards but was included in the standards “to provide a more 

formalized approach and more regulatory clarity.” 79 Fed. Reg. 72,906. The commenter stated 

that this statement does not excuse the EPA’s failure to reconsider entirely its statement of basis 

and purpose for the proposed rule with the affirmative defense for malfunctions removed. The 

commenter stated that, in the first place, the affirmative defense was a key element of the EPA’s 

explanation for why it was lawful for the Agency to promulgate MACT standards that apply 

during malfunctions but that do not reflect what is achievable with available technology during 

malfunctions. See Proposed Rule, 77 Fed. Reg. at 8599-8600. The commenter stated that the 

Agency believed at the time that an affirmative defense provision was necessary to effectuate the 

congressional directive that MACT standards be based on what is achievable with available 

technology; otherwise, the EPA would have had no statutory authority to promulgate the 

affirmative defense. The commenter stated that they believe that the EPA staff almost inevitably

had to have considered the effect of the affirmative defense on compliance obligations when they

were deriving the proposed standards. The commenter provided the recent example of the 

MACT standard for boilers and process heaters in which the EPA revised its MACT floor 

calculation to factor in periods of malfunction that did not qualify for affirmative defense. The 

commenter stated that having taken the affirmative defense into account when deciding what 

emission standards to include in the proposed rule, the EPA cannot now eliminate the affirmative 

defense without reassessing the appropriateness of those emission standards and how they will 

affect secondary aluminum plants if the standards are no longer mitigated by the affirmative 
86

defense. The commenter stated that the EPA must then publish its analysis and seek public 

comment on it before promulgating a final rule that makes emission limitations based on data 

from normal operations applicable even during malfunctions but deletes any affirmative defense 

for malfunctions.

Commenter 0298 stated that the court decision cited as the reason for eliminating the affirmative 

defense provisions said nothing about (a) whether the EPA must consider the effect of 

malfunctions when it sets emission standards that apply at all times (except during some startup 

and shutdown periods); or (b) whether it is appropriate for the emission standards themselves to 

contain an alternative emission standard that applies during malfunction events that meet certain 

criteria. The commenter stated that while the court decision is grounds for the EPA eliminating 

the affirmative defense as it was written in the proposed rule, it in no way authorizes the EPA to 

remove the affirmative defense from the emission standards without substituting some other 

provision addressing malfunctions; nor does it allow the EPA to remove the affirmative defense 

without even considering whether/how the remainder of the emission standards must be revised 

in light of the removal of the affirmative defense.

Commenter 0290 stated that they object to the EPA eliminating the Affirmative Defense, to the 

extent those provisions may be interpreted to require compliance with emissions limits during a 

malfunction contrary to established law. The commenter stated that although it reasonable for a 

source to meet operational requirements during a malfunction that minimize emissions, during a 

malfunction a source cannot be expected meet the same emissions limitations designed for 

normal operations. 

Commenter 0295 stated that they are concerned that the removal of the affirmative defense 

provisions will lead to an expectation that emission limits must be complied with during 

malfunction periods, even with the clear language to the contrary in the proposed rule preamble. 

The commenter stated that the proposed approach of offering only enforcement discretion does 

not provide an adequate regulatory framework for facilities managing malfunction events. The 

commenter requests that the EPA reconsider its position and establish reasonable standards for 

malfunctions, rather than leaving a vague regulatory framework that could allow biased agency

action or third party litigation for unavoidable situations. The commenter stated that due to the 

number and nature of potential malfunctions, establishing numerical emission limits is not 

technically feasible or practicable. The commenter recommended that the EPA establish 

malfunction work practice (such as a written malfunction response plan) and/or other alternative 

standard in place of the numerical MACT emission limits that were developed from normal 

operating conditions. 

Commenter 0296 urged the Agency to exercise its case-by-case enforcement discretion to 

provide flexibility as often as necessary in the event of violations caused by malfunctions.
87

Response: The EPA received numerous comments on the affirmative defense to civil penalties 

for violations caused by malfunctions that the EPA proposed to include in the rule. Several 

commenters supported the affirmative defense or supported the affirmative defense but made 

suggestions for revisions to its provisions. Other commenters opposed the affirmative defense or 

various components of the affirmative defense.

As discussed in the 2014 supplemental proposal, the D.C. Circuit Court vacated an affirmative 

defense in one of the EPA’s Section 112(d) regulations. NRDC v. EPA, 749 F.3d 1055 (D.C. 

Cir. 2014) (vacating affirmative defense provisions in Section 112(d) rule establishing emission 

standards for Portland cement kilns). The court found that the EPA lacked authority to establish 

an affirmative defense for private civil suits and held that under the CAA, the authority to 

determine civil penalty amounts in such cases lies exclusively with the courts, not the EPA. 

Specifically, the Court found: “As the language of the statute makes clear, the courts determine, 

on a case-by-case basis, whether civil penalties are ‘appropriate.’” See NRDC, 749 F.3d at 1063. 

In light of NRDC, the EPA in the 2014 supplemental proposal withdrew the proposed 

affirmative defense and is not including a regulatory affirmative defense provision in the final 

rule. In the event that a source fails to comply with applicable CAA section 112(d) standards as a 

result of a malfunction, the EPA’s ability to exercise its case-by-case-enforcement discretion to 

determine an appropriate response provides sufficient flexibility in such circumstances. Further, 

as the D.C. Circuit recognized, in an EPA or citizen enforcement action, the court has the 

discretion to consider any defense raised and determine whether penalties are appropriate. Cf. 

NRDC, 749 F.3d at 1064 (arguments that violation was caused by unavoidable technology 

failure can be made to the courts in future civil cases when the issue arises). The same is true for 

the presiding officer in EPA administrative enforcement actions. In light of the EPA’s 

withdrawal of the proposed affirmative defense and the absence of an affirmative defense in the 

final rule, we are not responding to the comments opposing or suggesting revisions to the 

proposed provisions to establish an affirmative defense. With respect to comments that supported 

the affirmative defense or argued that further analysis or rule changes were necessary if the 

affirmative defense is not adopted, the preamble to the final rule, sections 5.1 and 5.2 above, and 

this section provide the EPA’s reasons for not including an affirmative defense provision in the 

final rule as well as other responses.

Some commenters assert that EPA must reconsider its proposed decision to apply existing 

Subpart RRR standards to periods of malfunction in light of the withdrawal of the proposed 

affirmative defense, because the affirmative defense was necessary to ensure the MACT 

standards are achievable. A commenter cites an example of the EPA revising the MACT floor 

calculation for another source category to consider malfunctions. First, we disagree that the 

proposed affirmative defense was “necessary” to support the approach to malfunctions in the 

proposed rule (or in this final rule). As discussed above, we also disagree with the commenters’ 

views regarding the term “achievable” as that term is used in section 112. Further, in reviewing 

the comments received on the 2012 proposal and 2014 supplemental proposal and developing the 
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final rule, the EPA has considered all of the issues raised by commenters concerning the 

appropriateness of applying the existing Subpart RRR MACT standards to periods of 

malfunction and has concluded that the approach remains both consistent with the Act as 

interpreted in relevant court decisions and appropriate as a regulatory and compliance assurance 

policy matter. The fundamental analyses and considerations that support our approach to 

addressing violations caused by malfunctions was not affected by the withdrawal of the proposed 

affirmative defense. We again note that the malfunction exemption from Subpart RRR emission 

standards has not existed for several years, since it was vacated by the court, and we have 

received no indication from commenters or others of compliance problems or related 

enforcement responses or actions for this source category based on violations caused by

malfunctions. Indeed, no commenter identified even a single actual case of a Subpart RRR 

compliance issue caused by a malfunction. Based on this record, we believe EPA’s case-by-case 

enforcement discretion, as well as the discretion of a court in an enforcement action, to 

determine an appropriate response, including consideration of any defense raised concerning 

malfunctions and whether penalties are warranted in light of relevant facts, is a reasonable 

approach to malfunctions.
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6. Regulatory Impacts

Comment #1: One commenter (0199) discussed the history of regulatory activities and 

agreements involving the commenter, the U.S. EPA, including Regional offices, state agencies, 

and the U.S. Department of Justice; cumulating with a Consent Decree (attached to the 

comment) and guidance regarding subpart RRR . The commenter stated that as a consequence of 

these negotiations, it was determined that the commenter would request formal alternative 

determinations from the EPA, which would be acted on and issued. The commenter has since 

operated all of its facilities using this agreed-upon guidance which has, to date, been fully

accepted and utilized by the respective states and the EPA Regions in their role administering the 

Subpart RRR NESHAP rules.

The commenter expressed concern that the terms of certain provisions of the proposed changes 

to the Subpart RRR NESHAP rules because they seem to change or otherwise limit agreed-upon 

guidance which took extensive time and effort to develop and which has proven to be very

helpful to both the commenter and the Government in the interpretation of the meaning and 

intent of these very complicated rules. 

Response: The requirements of these final amendments apply even if an individual facility is 

operating under a consent decree that previously established less stringent requirements.

6.1 Cost and Economic Impacts

Comment #1: One commenter (0192) stated that because of safety concerns and the cost burden 

of installing capture systems for performance testing on uncontrolled group 1 furnaces, facilities 

will likely decide to not classify additional furnaces as group 1, and those furnaces will not 

recycle purchased scrap, reducing recycling rates, using more expensive and energy-intensive 

primary aluminum. The commenter noted that the EPA did not include this increased expense to 

facilities in its economic impact evaluation. 

Response: We do not agree that there will be any measurable decrease in secondary aluminum 

recycling rates related to the requirements for performance testing on uncontrolled group 1 

furnaces.

Comment #2: One commenter (0192) noted that the EPA claimed a net benefit of $600,000 to 

“Allow Furnace Switching.” The commenter maintained that the proposed rule does not freely

allow furnaces to switch classifications, it severely restricts when a change can occur and 

requires redundant and unnecessary testing to do so. The commenter asserted that the EPA failed 

to include any cost to account for the downtime that facilities will experience when a baghouse 

malfunctions and a furnace classification change is prohibited or delayed by the proposed rule. 

The commenter estimated that this restriction could cost in excess of $1 million for a facility (the 

commenter provided the basis for this cost estimate in a separate Confidential Business 

Information submittal). The commenter claimed that the EPA did not include costs to account for 

unnecessary operation of baghouses when facilities are compelled by business conditions to 

process more expensive aluminum feedstock than is necessary if they had the flexibility to 

change furnace classifications to a group 2 Furnace or a group 1 Furnace without add-on control 
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under the conditions set forth in the February 16, 2012 Applicability Determination. The 

commenter stated that the EPA did not include an estimate of the additional testing requirements 

included in section 63.1514, or the costly requirements and restrictions to operational flexibility.

The commenter stated that the EPA did not provide cost estimates for the requirement requiring 

the operation of control devices when furnaces are idled for less than 24 hours, which the 

commenter believes is unnecessary; the 60-day waiting period before a revised OM&M Plan can 

be implemented, which the commenter believes reduced facility’s flexibility; or the regulatory

burden on area sources to submit annual compliance certifications.

Response: As discussed above, in response to comments, the EPA will allow up to 4 furnace 

switches in any 6-month period. Therefore, we do not expect any cost associated with downtime 

when a baghouse malfunctions, because we do not anticipate that a furnace classification will be 

prohibited or delayed by the final rule. 

Prior to the promulgation of the 2015 amendments, the rule required that furnace control devices 

operate at all times. However, the 2015 revised rule allows control devices to be shut down when 

furnaces will be idled for more than 24 hours as a means to provide operational flexibility and 

cost savings when furnaces are idled over weekends or extended holidays. Therefore, this allows 

more flexibility and involves less cost, not any additional cost.

We have removed the 60-day waiting period before a revised OM&M Plan can be implemented

as well as the requirement for annual compliance certification for area sources. 

Comment #3: One commenter (0191) cautioned the EPA to validate the actual size and scope of 

the regulated community subject to the subpart RRR rule. The commenter indicated concern over 

the initial ICR distribution list being derived incorrectly, erroneously identifying a number of 

facilities as Secondary Aluminum Production sources subject to the Subpart RRR rule. The 

commenter expressed concern that some of the 166 facilities that the EPA maintains are subject 

to the Subpart RRR rule might be facilities that either did not understand the applicability

definition or had completed the ICR prior to being advised that it did not in fact apply to their 

facility. The commenter questioned the estimate of the number of facilities the EPA believes are 

actually subject to the rule may be overstated, thereby also calling into question all of the 

estimates on costs and benefits contained within the rule.

Response: As described in the memorandum, "Development of the RTR Risk Modeling Dataset 

for the Secondary Aluminum" (docket item EPA-HQ-OAR-2010-0544-0149) we believe there 

are approximately 161 facilities within the Secondary Aluminum Production source category. It 

is unlikely the number of facilities is overestimated because, as part of the risk modeling process, 

we identified facilities that had equipment regulated under Subpart RRR based on ICR responses

. We also believe it is unlikely that a significant fraction of the facility owners who responded to 

the ICR erroneously stated to the EPA that their facility is subject to Subpart RRR. We note the 

commenter did not provide specific information about any individual facilities. We believe our 

estimate of the number of facilities subject to subpart RRR remains accurate although, in 

response to comments on the 2012 proposal and the 2014 supplemental proposal, we have 

revised certain estimates of costs and benefits. These are described in the preamble to this final 

rule.
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7. Miscellaneous Comments

7.1 Commenter Endorsements

Comment #1: One commenter (0193) supported the comments of Alcoa and Coalition for 

Responsible Waste Incineration (CRWI) (Commenters 0194, 0190).

Response: The EPA has responded to the comments of Alcoa and the Coalition for Responsible 

Waste Incineration (CWRI) (Commenters 0194, 0190). 

Comment #2: One commenter (0194) supported the comments of the Aluminum Association 

and the Coalition for Responsible Waste Incineration (0193, 0190).

Response: The EPA has responded to the comments of Alcoa and the Coalition for Responsible 

Waste Incineration (CWRI) (Commenters 0194, 0190).

Comment #3: One commenter (0192) supported and agreed with the Aluminum Association’s 

(Commenter 0193) comments and evaluation concerning the overestimate of risk in the EPA’s 

risk assessment calculations due to HAP emissions from secondary aluminum facilities. The 

commenter stated that to the extent not inconsistent with the comments provided herein, it 

incorporates by reference TAA’s comments on the proposed rule.

Response: The EPA has responded to the comments of The Aluminum Association (Commenter 

0193). 

Comment #4: One commenter (0199) supported the comments of the Aluminum Association 

(0193).

In a comment on the supplemental proposal, commenter 0290 stated that, to the extent consistent 

with their submitted comments, they incorporate by reference TAA’s comments on the proposed 

rule.

Response: The EPA has responded to the comments of The Aluminum Association.

7.2 Other Comments

Comment #1: One commenter (0183) asked for an extension of the comment period.

Response: The comment period was extended from March 30, 2012 to April 13, 2012.

Comment #2: A commenter (0191) asked that the EPA incorporate by reference the full text of 

the Subpart ZZZZZZ rule into the docket for the current rulemaking, drawing specific notation to 

the language pertaining to the performance testing and monitoring requirements established for 

aluminum foundries subject to the rule.

Response: There is no need to incorporate Subpart ZZZZZZ into the docket for the current 

rulemaking, because it is already available in the Code of Federal Regulations. 
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Comment#3: One commenter (0019) stated support for regulations that protect environmental 

safety.

Response: The EPA acknowledges the commenter’s support.

Comment #4: In a comment on the supplemental proposal, commenter 0298 stated that they

incorporated by reference their comments on the 2012 proposal.

Response: No action needed on this comment as their comments on the 2012 proposal are 

addressed elsewhere.

Comment, #5: In a comment on the supplemental proposal, commenter 0295 stated that in 

addition to their comments on the 2014 supplemental proposal, they note that many of the items 

it commented on in comments provided on April 13, 2012 regarding the proposed rule noticed on 

February 14, 2012 (77 FR 8576) will not be addressed until final rule promulgation expected in 

August 2015. The commenter stated that given the inter-relatedness of the 2012 comments with 

those being provided here, they stress the continued validity and applicability of its 2012 

comments to this supplemental proposed rulemaking as well as reiterates their applicability to 

the original 2012 proposed rule.

Response: No action required; their comments on the 2012 proposal are addressed elsewhere.

Comment #6: In a comment on the supplemental proposal, commenter 0296 stated that the 

proposal defines the secondary aluminum industry as consisting of approximately 161 secondary

aluminum production facilities, of which the EPA estimates 53 to be major sources of HAP. The 

commenter stated that it is a matter of continuing concern that the applicability definition for the 

current proposed revision to the subpart RRR rule still lists “Aluminum Foundry Facilities: 

NAICS 331524, and Aluminum Die-Casting Facilities: NAICS 331521” among the Industrial 

Source Categories affected by this proposed action. The commenter described the basis for their 

concerns regarding the potential erroneous classification of foundries and die casters as 

secondary aluminum production facilities. The commenter stated that there may still be reason to 

question the categorization of some of the facilities the EPA believes are actually subject to the 

rule, and therefore urge the agency to use caution in applying the applicability definition to the 

Industrial Source Categories it feels may be are affected by this proposed rulemaking.

Response: The list of industrial source categories, including aluminum foundry facilities and 

aluminum die-casting facilities, in Table 1 of the preamble to the supplemental proposal is a 

“guide for readers regarding the entities likely to be affected” and is not an “applicability 

definition” for the Subpart RRR rule. As stated plainly in the preamble, “[t]o determine whether 

your facility would be affected, you should examine the applicability criteria in the NESHAP.” 

79 FR at 72876. The applicability section of subpart RRR appears at 40 CFR 63.1500. The 

commenter did not suggest specific changes to the rule and we do believe that the comment 

warrants making any changes to the rule.

Comment #7: In a comment on the supplemental proposal, commenter 0296 stated that they 

concur with the Agency's determination that there have been no new developments in practices, 

processes or control technologies that are applicable to the secondary aluminum production 

source category.
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Response: We acknowledge and appreciate the commenter's views.